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Guys,
These r my subjects. So if u have any doubts or want to share some tips, pls go ahead. I'll try to answer all ur questions asap........others can join in to help(of course).
There's no common thread for these subjects and so I thought of having one. It'll be easier.
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A question set by my teacher, not sure where he got it and I have no clue about it.
The allele for a normal haemoglobin is In. The allele for a sickle cell haemoglobin production is Is. Explain why under some circumstances people who are heterozygous for this condition have a greater chance of survival than homozygous people.
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This is pretty easy. Sickle cell anaemia is caused by a mutation in the blood. When the faulty haemoglobin is present the red blood cells become sickle-shaped, especially when oxygen levels in the blood become low. So these cells r less efficient in transporting oxygen and more likely to get stuck in the capillary, preventing blood flow. The faulty allele is dominated by the normal haemoglobin but has some effect in a heterozygous genotype.(not life-threatening)
Malaria is a life-threatening disease caused by a parasite that invades red blood cells. A person who is heterozygous has a protection from malaria, because the parasite is unable to invade and reproduce in these cells. A person who is homozygous for sickle cell also has high protection but is likely to die from sickle cell anaemia whereas a person with normal haemoglobin is at a high risk of contracting malaria.
The distributions of malaria and sickle cell on the map coincide in tropical areas because of the selective advantage of the sickle cell allele in providing protection against malaria.
I hope u've understood
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K thanks
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my pleasure :)
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can u explain the functions of the lymphatic system?
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for our syllabus this is all we need to know. Lymphatic system is really complicated if u try goin' into details. So here it is
Three functions
-The return of tissue fluid to the blood in the form of lymph fluid. This prevents fluid build-up in tissues.
-The production of lymphocytes(very imp). These r made in the lymph glands such as the tonsils, adenoids and spleen. The glands become more active during the time of an infection because they r producing and releasing large no of lymphocytes.
-The absorption of fatty acids and glycerol from the small intestine. Each villus contains a lacteal- a blind ending lymph vessel which absorbs the fatty acids and glycerol.
This is all u need to know. Don't get urself confused by trying to unlock the whole working of the lymphatic system. It's there in detail in the A levels. For now this is it. Hope uve got the functions.
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Could you help in details about the kidney tubule (nephron)?
Like the glomerulus, and stuff?
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cud nid404 help me wit nov 01 p6 of bio..its urgent..please
i m not sure of my answers..
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nid404
the biology specialist
looks like he wants to go in medical
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yup. I can help u with the process.
Blood is got to the kidney via renal artery. The renal artery divides into a great number of arterioles and capillaries, mostly in the cortex. Each arteriole leads to a glomerulus. The pressure in the glomerulus causes part of the blood plasma to leak the capillary walls. The RBC's and proteins in plasma r too big to pass out. The fluid that moves out contains mainly water with dissolved salts, urea, glucose and uric acid. The process by which the fluid is filtered out of the blood by the glomerulus is called ultrafiltration. The filtrate from the glomeruls collects in the renal capsule and trickles down the renal tubule. As it does so, the capillaries which surround it absorb the substance the body needs. All the glucose is absorbed, with much of the water(depends on the state of hydration). The some salts r taken back to keep the correct con in the blood. This process of taking back the required substances is called selective reabsorption.
Substances that r not needed pass further down to the collecting duct into the pelvis of the kidney. From here the fluid, now called urine, passes down the ureter to the bladder.
Nephron- A single glomerulus with its renal artery, renal tubule and blood capillaries
visit the site for a good animation http://www.biologymad.com/resources/kidney.swf
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nid404
the biology specialist
looks like he wants to go in medical
y do ull change ma gender all the time. By the way i want to work for conservation of wildlife. And w8 help in nov 2001 do u want 2009scared???
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guys i will get back to u later. sorry 2009 scared i can't ans rightaway but i promise to get back. Please tell me the questions ur having difficulties with.
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thanks nid!
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ur welcome and thanks to u too for acknowledging :)
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Urgent!!
Has anyone been examined biology paper 6 !!
If yes please tell some questions included in the exam!
Thanks!
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won't get any help. Nobody will help u with that.U hav doubts i'll clear them.
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I'll be back in some time.post ur doubts here and i'll get back.
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Hey..... :D
i need help in the co-ordination and nervous system.
like how the impulses triggered by the sensory neurone cause the person to put a hot item down...
and the whole white/grey matter and the dorsal thing... :-\ im not so sure...
oh, do you thing we would be asked about volume of respirated air (like the types of breathing)?
and the muscle/skeletal system.... will that come out?
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http://e-subjects.co.uk/mod/resource/view.php?id=2026 This will solve your nervous sytem prob
And they might ask u for the volume of respirated air and percentage of different gases during inhalation and exhalation. visit http://en.wikibooks.org/wiki/GCSE_Science/Breathing_and_Respiration and have alook at the ppt attached
Learn spinal cord here http://www.becomehealthynow.com/article/bodynervousadvanced/820/
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hope uve liked it archangel
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AHH THANK YOU SOO MUCH ;D
+ rep for you =)
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Guys,
These r my subjects. So if u have any doubts or want to share some tips, pls go ahead. I'll try to answer all ur questions asap........others can join in to help(of course).
There's no common thread for these subjects and so I thought of having one. It'll be easier.
cn u please gimme d answers 4 nov 01...q3 n q1 please
i m confused
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I suppose this is paper 6
well, for q1
a)i) potato A will be turgid whereas B will be bent downwards.
ii) Explain the effect of the solution it is placed in
B is in a conc solution so water potential in potato strip is higher than the solution. This causes water to move out of the strip, down the concentration gradient. This results in loss of mass of the strip and the mass hanging from it causes the strip to bend.
iii) Draw a plant cell .The cell cytoplasm should be shown as pulled away from the membrane. check the image(http://leavingbio.net/OSMOSIS%20AND%20DIFFUSION_files/image021.gif)
b)RBCs r animal cells and so do not have a cell wall. Cell walls prevent the cell from bursting. When placed in water, water travels into the cell and since there's no cell wall the cells burst.
I haven't done the graph for q3 but I can help u with the rest of it.
b)ii) For this question explain the process of transpiration(loss of water from leaves leading to a loss of mass)
iii) There can be other methods too but I think this is the most [preferred method
-Apply vaseline on the lower surface of the leaf.hang the leaf.
-Keep a cobalt chloride paper close to the upper surface of the leaf.
-the cobalt chloride paper turns pink in presence of water. This shows there is loss of water from the upper surface which results in loss of mass.
I hope this is fine
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Thanks for your help on the kidney, especially the animated diagram - that was so helpful!!!
Thank a lot!
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nid404...
u r AMAZING...... :D
But did you notice that ppl are not asking abt chemistry??
This proves that biology is harder... :o
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probably but these two r my fav
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I prefer maths, chemistry and physics... don't like biology ::)
So I might come back at any time for questions ::)
am I welcomed?? ... (anyway you seem helpful) :D
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of course u r. What kind of question is that????
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I don't knw,
but now I have my teacher (u) if I have any doubts ;)
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yup but i hope i don't end up being a teacher..........like for real
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This will be a disaster :o
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guys I'm goin' to brush up my biology for tom but u keep posting ur doubts. I'll come online after 4-5hours and clear them.
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ill ask about bio paper 3 l8er. Right now ppl should be asking about paper 6. I have a question. Usually they ask you to draw a labeled and enlarged image of some organism that they give u a pic of. HOW ARE YOU SUPPOSED TO KNOW THE PARTS? I did one paper where they ask you to draw a labeled image of an apple. Theres one more where they ask you to draw a labeled image of a slug. I mean... HOW? We havent learned the parts and theyre not in my textbook. Any enlightenment?
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i've studied for all the external features from D.G Mackean and the guide.
U just need to know the external features for different vertebrates and invertibrates.
Vertebrates- Mammals, birds, reptiles, amphibians and fish
Invertebrates- Nematodes, Molluscs(slugs),Annelids, Arthrapods(arachnids, insects, myriapods, crustacean)
And about the fruits....don't bother much
just name the seed cotyledon in the tranverse section and stalk/petiole. Pericarp(ovary wall ),mesocarp(flesh), exocarp(skin)
but really don't stress urself with this.
learn parts of the seed well.
i've got a few sites http://www.kidport.com/RefLIB/Science/Animals/Animals.htm and http://www.authorstream.com/Presentation/jagmeet.smart-119180-classification-animals-classificationofanimals-education-ppt-powerpoint/
tell me if u need more help
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seems like ull have no doubts now..... Then ill get back to studying and return later to solve ur doubt if any
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hey uhm..
How would you compare the rate of uptake of the coloured solution by the plant (you know in this experiment when they put a plant into coloured water, to observe how the water travels up the plant), with another plant that has had its roots cut off?
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Hey
I need help with this question
1. How are the plumule and radicle of a broad bean protected as they are pushed outwards into the soil?
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hey uhm..
How would you compare the rate of uptake of the coloured solution by the plant (you know in this experiment when they put a plant into coloured water, to observe how the water travels up the plant), with another plant that has had its roots cut off?
take same species and age of plant. then cut off the root of one plant then place both plants in the same amount of dye. then measure initial volume then later measure the final volume of both of the plants.
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shogun u missed 1 point. keep the plants for the same time in the water and let all other external conditions be same.
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Thanks guys =]
we measure the volume of coloured water before and after the experiment (for both plants) and compare the differences right? Is the coloured solution gonna change the colour of the leaves? And if it is, is the colour gonna be more intensive for the plant that took in more water (with the roots)?
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Hey
I need help with this question
1. How are the plumule and radicle of a broad bean protected as they are pushed outwards into the soil?
i dunno where u got his q from cuz its not in our syllabus. anyways the answer to this is the tip of the root contains loose cells called root cap which protect the tip from damge as it penetrates into the soil. As for the plumule since the bean seeds are dicots the epicotyl pulls plumule backwards and prevents damage. I mean it curls up. HAVE A LOOK AT THE WORD FILE ATTACHED. SHOWS THE STAGES OF GERMINATION A BROAD BEAN SEED
and sugar the color will most likely be visible. to compare color change a colorimeter can be used. It will show a higher reading with the plant with roots.
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Thanks Nid. We werent taught the mesocarp pericarp thing so it was a big help.
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k guys ill be there for bio and chem. so if u got anything to ask go ahead.
I may not come online very often when the theory papers start. But i'll help whenever i can.
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hey i hav two doubts nid!
dey usually ask us where in the alimentary canal, most of the fibre or roughage is..wt do we say for dat? large intestine? wts the explanation?
and the other doubt is dat,
wt is the difference in structure b/w a sensory neurone and a receptor neurone? also, do you by any chance hav pics of the two neurones, and which one is which, cuz dey ask us this q in mcqs..?
thanks a ton :)
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http://www.medtropolis.com/VBody.asp visit this site it's really good.
roughage/fibre cannot be digested.
fibre passes through the alimentary canal undigested.It thus finally reaches the large intestine and it absorbs large amounts of water on its way along the canal and the intestine, resulting in softer and bulkier stool .
(http://content.answers.com/main/content/img/elsevier/dental/f0429-01.jpg)
The motor neurone sends impulses from the brain/spinal cord to the effectors whereas sensory neurones send impulses to the spinal cord/brain.
and ive attached a ppt. let me know if u need any help
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hey aquarian93 hope info reaches u before the exam.
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guys here's a site for ull to practice multiple choice questions for each topic.
http://www.fed.cuhk.edu.hk/~johnson/interactive_MC/eng_selection.html
and notes http://revisioncentre.co.uk/gcse/biology/index.html
tell me if u guys like it
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guys, y don't ull post the questions here cuz there r so many topics i find it difficult to shuffle and i can really help ull with bio and chem.
So hope to see some questions when im back. :)
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cud sum1 explain the nitrifying denitrifying nitrogen fixing bacteria?
wat does the nucleus in every body cell of a male contain?
X allele
y allele
y chromosome
y gene
urgent help needed now!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! >:(
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cud sum1 explain the nitrifying denitrifying nitrogen fixing bacteria?
wat does the nucleus in every body cell of a male contain?
X allele
y allele
y chromosome
y gene
urgent help needed now!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! >:(
are you sure the question is right? is it in any paper?
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cud sum1 explain the nitrifying denitrifying nitrogen fixing bacteria?
wat does the nucleus in every body cell of a male contain?
X allele
y allele
y chromosome
y gene
urgent help needed now!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! >:(
are you sure the question is right? is it in any paper?
\
yup its in jun 99
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cud sum1 explain the nitrifying denitrifying nitrogen fixing bacteria?
wat does the nucleus in every body cell of a male contain?
X allele
y allele
y chromosome
y gene
urgent help needed now!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! >:(
are you sure the question is right? is it in any paper?
\
yup its in jun 99
my june 99 got 20-30 missing..lool
well..apparently..the answer is y-chromosome..X-Y are neither genes, nor alleles..we consider them chromosomes..and in additon..every bod cell has XY chromosome..which means..it always has X and alwas has Y chromosome.
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cud sum1 explain the nitrifying denitrifying nitrogen fixing bacteria?
wat does the nucleus in every body cell of a male contain?
X allele
y allele
y chromosome
y gene
urgent help needed now!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! >:(
are you sure the question is right? is it in any paper?
\
yup its in jun 99
my june 99 got 20-30 missing..lool
well..apparently..the answer is y-chromosome..X-Y are neither genes, nor alleles..we consider them chromosomes..and in additon..every bod cell has XY chromosome..which means..it always has X and alwas has Y chromosome.
haha weird!
thanks alot
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hey Kim,
sorry for the delay but insanity-stricken has correctly said Y chromosome
Remember in females it's XX and males it's XY
so the sex is determined by this
Only if the Y chromosome from the male combines with the females X chromosome will a boy be born
If X chromosomes from both combine it will be a girl
@ insanity-stricken: thanks for answerin it
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I thought perhaps people will have many chem doubts just b4 the exam, so I made this thread...its better if we have all chem question in one thread rather that making new ones for each question.I start:
1)Design and draw an apparatus that could be used to collect the volume of hydrogen produced when zinc is added to dilute hydrochloric acid.
2)A solution gives a white ppt which is soluble in excess with sodium hydroxide. Its reaction with aq. ammonia gives a white ppt which is insoluble in excess. Find out the cation present in the solution.
okay, so i know how to design the experiment(as in the description) but i wanted a neat diagram plss.
nd for the second question, there can be 2 answers- Aluminum and Lead.....so which one should i write??
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the first one can be like this (attached)
the second one, umm, i guess it shud be aluminum because lead isnt dere in the book . which past paper is this?
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Thanks for the diagram aadi...dts wt i wanted...
for the second, its from an o level past paper...actually i have a revision book from o levels...nd the question is from
"N2002 P3 A2a"
that is what is written, bt i tried o level nov 2002 p3..bt dts a practical...i dunno..
see if u know which paper it is nd let me know!!
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Some1 could draw the stuff for you
For the second part.......Aluminium ions can be distinguished fromlead ions by the insolubility of lead chloride. So U add dil. HCl to the mixture If colorless solution is formed it is aluminium ions. If a white ppt remains, then it's lead
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but nid my practical paper is over...this question is from the structured paper(p3).....i can't do those reactions in the examination hall :P
Thanks anyways...plss see if u cud help an better
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but nid my practical paper is over...this question is from the structured paper(p3).....i can't do those reactions in the examination hall :P
Thanks anyways...plss see if u cud help an better
ok ill check da paper.....something has to be mentioned
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oh yeah nd for the first one......hydrogen can be collected over water in an inverted calliberated glass jar....
both the ways of collectin in the diagram.....short cut...haha....m too lazy naa
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lol...nid u r toooooooooooooooooooooooo lazzzyyyy!!!!!!!!! :P ;D
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the paper damn.......it's different......can u type the question exactly the way it is given
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see the question has not been given to me....i mean the second one is not a question given to me...i asked it...cuz i saw tthis in the qualitative analysis table nd was a little confused....
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see the question has not been given to me....i mean the second one is not a question given to me...i asked it...cuz i saw tthis in the qualitative analysis table nd was a little confused....
abbe then...they will tell you the result with HCl
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why cant you just right wat nid told you in the paper??
u'll get the marks!!
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okk...thanks nid nd aadi!! ;D
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okk...thanks nid nd aadi!! ;D
in case they don't mention the HCl reaction.....write both...they won't cut ur marks....they'll be impressed :D
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lolzz!!!
good trick!!
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in case they don't mention the HCl reaction.....write both...they won't cut ur marks....they'll be impressed :D
lol!! :D
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she is lazy but toooooooooooo chalu!!!
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she is lazy but toooooooooooo chalu!!!
call me smart....i'd appreciate that ::)
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ok!!!
smartly chalu + lazy!! :P :P
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hey bt wait m not always lazy.....I'm very active if there's summin interesting....like obv i can't be lazy while im playing bb or swimming or summin like that......so yea....depends
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ohh..!!
true!!
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so we can call u a smart girl with some traits of laziness.....hows it???lol...
By the way guys i think letsleave this thread for chem at least untill the exam dude!!!ppl will have many questions
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so we can call u a smart girl with some traits of laziness.....hows it???lol...
By the way guys i think letsleave this thread for chem at least untill the exam dude!!!ppl will have many questions
hows it?? u want me to let u knw.....hahaha.....U haven't seen me fighting wid guys....like physically....u've missed it....I am very active then
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never heard abt ur fights from aadi!!
i am sure even he might not know this!!1
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never heard abt ur fights from aadi!!
i am sure even he might not know this!!1
no 1 knows.....i don't tell any1 at home....they'd stop me from goin to school.....
I once bashed a guy cause he didn't throw the chocolate wrapper in the bin....warned him tho....he took it lightly :D
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baapre!!
tereko namaskar!!!
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baapre!!
tereko namaskar!!!
namaskar....lol
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sachi yaar!!
i have heard this for first time!!
girl hitting a boy!!
LMAO!!
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sachi yaar!!
i have heard this for first time!!
girl hitting a boy!!
LMAO!!
wanna experience it?..nid404 is coming to navi mumbai soon :P
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naa..!!
never!!!
By the way when is she coming!!
aadi sending u a pm check it!!
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adi bloody is full bones only.....so i used to hit him with the hard pillow....cover his face n stuff...rathe smash it...... :P
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adi bloody is full bones only.....so i used to hit him with the hard pillow....cover his face n stuff...rathe smash it...... :P
haddi logon ko marega toh joor se lagta hai!!
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how is hydrogen obtained from methane??
i know its a dumb doubt but plzz answer..
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how is hydrogen obtained from methane??
i know its a dumb doubt but plzz answer..
Diffusion, because of the difference in their relative molecular masses their rates of diffusion would differ.
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steam reforming reaction:
Ch4 + 2H20(g) --> CO2 + 2H2
dude eightas dts a method for separation of hydrogen from methane.....
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at the same temperature and pressure do all molecules of a gas move at the same speed???
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thanks adi...i had ritten methane and water and got that rong..though i cud get the equation
4got abt steam
thanks again
@eightAs - thats seperation
@adi - its a weird question, i guess yes, however if there are other particles like dust, some particles may move at different speed due to brownian motion
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Mis-interpreted it. I thought he meant obtain in the context of seperation.
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@adi_toxic- No. They don't move with the same velocity. There's an equation to find out the velocities of molecules......not for igcse...so don't bother..
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thanks adi...i had ritten methane and water and got that rong..though i cud get the equation
4got abt steam
thanks again
@eightAs - thats seperation
@adi - its a weird question, i guess yes, however if there are other particles like dust, some particles may move at different speed due to brownian motion
there are no other particles..its a sample of only carbon dioxide....then???
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in case they don't mention the HCl reaction.....write both...they won't cut ur marks....they'll be impressed :D
bt isnt the whole point of the qualitative analysis to differentiate between aluminum and zinc?
cos they both produce white ppt which dissolve in NaOH and aluminium produces insoluble white ppt in NH3 whilst zinc still produces a white ppt that dissolves in NH3..
isn't that why they mentioned ammonia? It's just bcos i've never heard of the HCl part,,
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@adi_toxic- No. They don't move with the same velocity. There's an equation to find out the velocities of molecules......not for igcse...so don't bother..
ohhkkk...u sure naa????
Thanks den....
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yaa im sure. Check the maxwell boltzman graph(attached) for an idea.....
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ooohhhhkkaaayyyy!!!!
bt i didnt understand anything from dt graoh lol.. :P
its kk i got my ans nid!!Thanks
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ooohhhhkkaaayyyy!!!!
bt i didnt understand anything from dt graoh lol.. :P
its kk i got my ans nid!!Thanks
oops!!
anyway u got it naa...bas :D
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yaaa...lol....thanxx!!!!!!
xD
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i gues the steam reforming method is given in TB!!
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whats TB???
text book??
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yup!!
pata nahin tha kya??
i was telling it to aadi tnot to you !!! abt TB
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yup!!
pata nahin tha kya??
i was telling it to aadi tnot to you !!! abt TB
TB is tuberculosis.....
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no it is tera bheja!!! :P :P
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no it is tera bheja!!! :P :P
it could be tera bacha also.......sh*t im goin nuts......no EADA here plz..
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age ka continued in EADA
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hey guys what's the definition of relative atomic mass??
don't explain it, cuz i already know what it means but what will be its precise definition for a 1 or 2 mark question??
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the mass of an atom on a scale where an arom of C-12 weighs exactly 12 units.
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ohhkk Thanks aadi....and relative molecular mass??
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the sum of relative atomic masses of all atoms in a molecule.
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tyvm again!! :)
done with add. maths??
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another one:
Which of them is endothermic ?
a)The formation of a hydrogen-chlorine bond
b)The formation of rust
c)The formation of water from ice
d)The formation of water from oxygen and hydrogen
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it shud b C
a) forming bonds -exo
b) reacts with oxygen, maybe exo
d) ofcourse exo.
for ice--> water, it has to melted i.e suply energy, and energy is taken in
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Even i think it should be C
thanks aadi
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yes ofc it's C
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ok people..here i am again...
Tungsten metal, W, is manufactured by reducing tungsten(III)oxide, WO3, whit carbon.
WO3 + 3C -----> 3CO + W
Calculate the mass of carbon needed to reduce 116g of tungsten(III)oxide.
-------------------------------------------------------------------------------------------------------------------------------
Now, I know how to do it.
We first take out the number of moles of WO3
which comes out to be 116/232 = 0.5 moles
Then, as the ratio is 1:3
Thus, the number of moles of C = 0.5*3 = 1.5 moles
Thus, the mass of carbon = 1.5*12 = 18g
Now my question,
if the ratio according to the equation is 1:3 for WO3:C
The how is it possible that for 116g of WO3 only 18g of C is required?
So, i thought maybe i have done it wrong although this is the correct method itself, but i still tried
Having the mass of WO3 as 116g and the ratio being 1:3
thus, the mass of C be 3*116 = 348g
But, the second method is wrong, isn't it?
then how are we getting 18g as the mass of Carbon required??
Please help guys!!!
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wats the answer?
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That's the problem dude...i don't have the answer...... :-[
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ok people..here i am again...
Tungsten metal, W, is manufactured by reducing tungsten(III)oxide, WO3, whit carbon.
WO3 + 3C -----> 3CO + W
Calculate the mass of carbon needed to reduce 116g of tungsten(III)oxide.
-------------------------------------------------------------------------------------------------------------------------------
Now, I know how to do it.
We first take out the number of moles of WO3
which comes out to be 116/232 = 0.5 moles
Then, as the ratio is 1:3
Thus, the number of moles of C = 0.5*3 = 1.5 moles
Thus, the mass of carbon = 1.5*12 = 18g
Now my question,
if the ratio according to the equation is 1:3 for WO3:C
The how is it possible that for 116g of WO3 only 18g of C is required?
So, i thought maybe i have done it wrong although this is the correct method itself, but i still tried
Having the mass of WO3 as 116g and the ratio being 1:3
thus, the mass of C be 3*116 = 348g
But, the second method is wrong, isn't it?
then how are we getting 18g as the mass of Carbon required??
Please help guys!!!
dude ur first method is right, ur second method is wrong. it doesn't matter what ur ans is as long as ur working is right. and also no need to get disconcerted by ur ans, it is likely u'll get such an ans cuz wolfram has such a high Ar
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what difference does it make if it has a high Ar????
i already said it myself that the first method is the right one...but the answer has to be a valid one dude...
u cant just right 24/6=7 if your calci says so....
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GUYS WHERE ARE YOU ALL?????????????????IS THERE NOBODY TO ANSWER THIS QUUESTION OR YOU GUYS DON'T WANNA HELP?? :P :P
PLEASE GUYS HELP ME OUT!!!!!
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what difference does it make if it has a high Ar????
i already said it myself that the first method is the right one...but the answer has to be a valid one dude...
u cant just right 24/6=7 if your calci says so....
Dude everything depends on moles. Mole ratio is 3:1. Masses follow because of moles.
Consider this
mass required = Moles required * Ar
So it depends on both Ar and mass
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dude i understand what u are saying but tell me what will be the answer to my question...the one that i have posted above....seee...the loooong one!!!
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ok people..here i am again...
Tungsten metal, W, is manufactured by reducing tungsten(III)oxide, WO3, whit carbon.
WO3 + 3C -----> 3CO + W
Calculate the mass of carbon needed to reduce 116g of tungsten(III)oxide.
-------------------------------------------------------------------------------------------------------------------------------
Now, I know how to do it.
We first take out the number of moles of WO3
which comes out to be 116/232 = 0.5 moles
Then, as the ratio is 1:3
Thus, the number of moles of C = 0.5*3 = 1.5 moles
Thus, the mass of carbon = 1.5*12 = 18g
Now my question,
if the ratio according to the equation is 1:3 for WO3:C
The how is it possible that for 116g of WO3 only 18g of C is required?
So, i thought maybe i have done it wrong although this is the correct method itself, but i still tried
Having the mass of WO3 as 116g and the ratio being 1:3
thus, the mass of C be 3*116 = 348g
But, the second method is wrong, isn't it?
then how are we getting 18g as the mass of Carbon required??
Please help guys!!!
This part is wrong. Mole ratio is 3:1 not the mass ratio. Hence, the second method is wrong.
-
dude i know the second part is wrong...i have already stated that....bt now tell me how can the first part be correct??
how can ther be only 18g of C to reduce 116g of WO3
-
now i have a meathod!!
if 1:3 rite??
1:3::116:x
so x=348 grams!!
check for the ans!!
-
arre shrey that answer is rong,
@adi - dude see,
232g of WO3 reacts with 36g of C rite?
so 116g with 18g of C
y do u find the answer weird, ?? check the ratio
232-36
116-18
looks quite clear to me..
-
ohhhh shrey!!!u back again with ur faltu replies.....
this has already been proved wrong....this method is wrong...read the question for what exactly m asking b4 replying...
nd y do u relate everything in the world with a ratio??
-
ohhhh shrey!!!u back again with ur faltu replies.....
this has already been proved wrong....this method is wrong...read the question for what exactly m asking b4 replying...
nd y do u relate everything in the world with a ratio??
i did not read your long meathod and explainations!!
By the way good ans aadi!!
-
arre shrey that answer is rong,
@adi - dude see,
232g of WO3 reacts with 36g of C rite?
so 116g with 18g of C
y do u find the answer weird, ?? check the ratio
232-36
116-18
looks quite clear to me..
1)why 36g of carbon???
2)m not saying the ratio is wrong, wht i am confued about is the fact that less reducing agent is required to reduce a large amount of the substance...
i mean how can only 18g of carbon be used to reduce 116gg of WO3
my question is more practical based than theoretical.
-
oye dude!!
it must be 36 cause 12 is atomic mass and we using 3 moles so 3*12=36!
-
ohhohhh...okk..got the first ans...Thanks vaan...bt my second one??
-
vaan?..where is vaan's answer??
oye dude
WO3's mol. mass - 232
3C's mol. mass - 12*3 = 36
so 232g with 36g
116 -> 18g
simple.
-
sorry i said vaan cuz i was reading smthng else simultaneously..sorry..
By the way Thanks shrey
-
this in not ratio propotion!!
so here you need to take mass of both carbon and WO3!!
where as you have taken 1:3 ratio of molecules!!
got it!!
-
1)why 36g of carbon???
2)m not saying the ratio is wrong, wht i am confued about is the fact that less reducing agent is required to reduce a large amount of the substance...
i mean how can only 18g of carbon be used to reduce 116gg of WO3
my question is more practical based than theoretical.
See, the things that actually do the work are molecules. 18g of Carbon contains 3 times more molecules than 116 gms of WO3 does. Three C molecules react with one WiO3. molecule. I hope you get it now.
-
yeah!!i think i'll have to compromise...cuz no1 actually understood my question...or perhaps m not able to convey exactly what i am confused about....anyways...thanks alot guys...
-
See, the things that actually do the work are molecules. 18g of Carbon contains 3 times more molecules than 116 gms of WO3 does. Three C molecules react with one WiO3. molecule. I hope you get it now.
ummm...i think that makes it a bit clearer...Thanks eightas
-
exactly. dont get confused by the mass ratio. the msas of C is less than that of WO3, but as eightAs already said, 1 molecule of WO3 reacts with 3 molecules of C!!
-
sorry i said vaan cuz i was reading smthng else simultaneously..sorry..
By the way Thanks shrey
kk!!
np!!
dude tereko kya nahin samjha??
why dont yu ask this to ur teacher??
-
yaa now that is what m gonna do tom when i go to school.....
-
hamlog ko bhi ans bata!!! :)
-
hamlog ko bhi ans bata!!! :)
Answer 18 gms hi hai yaar.
-
its 18g
-
its 18g
Yeah 116 was in the question sorry. i'll edit my post.
-
Thanks guys!!!
i dont think there's any need to ask my teacher now..but i'll still do so for complete clarification....
BEST OF LUCK TO U ALL FOR ANY EXAM THAT U HAVE TOM!!!!!!
gud night!!
-
thik hai!!
chal fir!!
-
guys .. what are all the equations u need to know for the production of sulphuric acid?
-
guys .. what are all the equations u need to know for the production of sulphuric acid?
S + 02 --> SO2
2SO2 + O2 <--> 2SO3 (at 1atm. pressure, 450'C nd vanadium (V) oxide catalyst)
SO3 + H2SO4 --> H2S2O7
H2S2O7 + H2O --> 2H2SO4
-
Hello ppl,
i have this question from the Igcse chem guide topic11 on pgno.56.
For the followin redox reaction write half equations, showing the electron transfer. Then identify the change which is oxidation an the reactant which is the reducing agent. Give reasn for each ans.
i knw the answers n the 1st part of forming an equation is not the prob. i have a prob wid the 2nd part, i'm not able to understand the explaination given in the ans behind. It says I- is the reducing agent but i think it is wrong.
If u think the ans given is right then plz explain me.
Hope u got my question!!
-
Hey buzywidbizworld
first of all the answer given at the back is right!
now the explanation:
the equation for Iodine is : 2I- - 2e- ---> I2
now as u can see the iodine is losing electrons and is thus oxidised(oil rig)
Whenever a substance is oxidised, it acts as a reducing agent
reason: because it is losing the electrons, which will later be gained by Cl to be reduced, therefore it is aiding Chlorine in getting reduced.
Do u get what i am trying to say?
Basically, always remember that whichever ion gets reduced acts as the oxidising agent and whichever gets oxidised acts as a reducing agent.
Tell me if you still didn't understand
-
Write an ionic equation for the precipitation of the insoluble salt, silver(I) chloride.
answer this if ne body can!!!
-
dude i did it in the other thread!!!!!!!!!!!!y u posting the same question everywhere!??
-
am in need of correct ans!!
so i am doidng tit everywhere!!
again someone!!
Write an ionic equation for the precipitation of the insoluble salt, silver(I) chloride
-
she's such a charmer oh no
-
she's such a charmer oh no
huh??
-
she's such a charmer oh no
he is out of his mind!! :P
-
hey guys plss answer:
out of Scandium, Iron, Tin, and Mercury
why is Mercury the best oxidising agent agent and Scandium the best reducing agent?>?>?
-
Hey buzywidbizworld
first of all the answer given at the back is right!
now the explanation:
the equation for Iodine is : 2I- - 2e- ---> I2
now as u can see the iodine is losing electrons and is thus oxidised(oil rig)
Whenever a substance is oxidised, it acts as a reducing agent
reason: because it is losing the electrons, which will later be gained by Cl to be reduced, therefore it is aiding Chlorine in getting reduced.
Do u get what i am trying to say?
Basically, always remember that whichever ion gets reduced acts as the oxidising agent and whichever gets oxidised acts as a reducing agent.
Tell me if you still didn't understand
Hey aditoxic!
Thanks alottt dude. I'm clear wid the ans nw. This concept of oxidation n reduction is tooo confusin for me but nw i hav got it.
once agn Thanks alot :)
-
ur welcome dude!!
-
TO AADI
Oxidation is loss of electrons
Reduction is gain.
An oxidising agent will gain electrons in the process
A reducing agen will lose electron in the process
So scandium has the lowest number of electrons, so it will be more prone to lose them. Thus best reducing agent.
Mercury needs one more electron to make full shell, so will be more prone to gain electrons. Thus best oxidising agent.
-
hey guys plss answer:
out of Scandium, Iron, Tin, and Mercury
why is Mercury the best oxidising agent agent and Scandium the best reducing agent?>?>?
mercury is least reactive nd scandium the most!!
so whenever scandium reacts it reduces the others!!
and also when mercury reacts it takes up oxygel
like mercuryoxide+Mg=MErcury+MgO2!!!
samjha!!
-
thanks dude....and thanks shrey...samajh gaya!!!
By the way dude...its adi for adi_toxic not aadi...dts the other one
-
hi
cud u also help me to ans this?
q- why should you be able to predict that metals such as iron and chromium have more thn one oxidation state?
wa8in 4 da reply.
-
i get confused. But, shrey is wrong. its to do wid electrons not reactivity.
-
why cant we do it as i said????
-
2 buzy
its becasue they are transition metals.
-
Its a redox question u see. and redox questions ask about valence electrons. So reacticity is about displacement reactions. But this is redox. and anyways, u r wrong, as transition metals behave differently under different circumstances.
-
hi
cud u also help me to ans this?
q- why should you be able to predict that metals such as iron and chromium have more thn one oxidation state?
wa8in 4 da reply.
1)because they are transition metals
2)due to their presence in different forms...ex, FeSO4 and FeCl3
-
for adi toxic's second point, its restating what they said in the q. unless u are given examples of same metals reacting differently, u shud not give the second point.
-
i think u should cuz just stating that they are transition metals doesn't score u full marks...if i remember correctly i have seen this point in some mark scheme
-
Thanks guys
but Dude aditoxic was ri8 wid da eg.
-
i do a level u see, i am starting to think more like an Edexcel markscheme. srry adi toxic, if u felt insulted!! :-[
-
llol...not at all dude...i was just trying to tell u that the point was valid that's it...no personal issues man
-
uhm..can anybody tel me de ionic equation for de reaction between calcium oxide nd hydrogn ionz? ???
-
CaO + H+ ---> Ca2+ + H2O
-
wont it be this?? CaO + H2= Ca2+ + OH- + H+ ... it mayb this not sure
-
CaO + H+ ---> Ca2+ + H2O
i think dts right!!
this is right... im sure about it :)
-
but isnt it always H2 and not H+???
-
no not always... Hydrogen can also b expressed as an ion.. it just depends on the question...
-
o got it :) :)
-
i thought aditox ws rite..bt how cn hydrogen combine wid o2?..Ca is mor reactive rite??
nits..its hydrogen ions..so h+..
-
arrey nits u gotta understand this...
its not a normal reaction between hydrogen and calcium oxide...
its the reaction for the treatment of acidity of the soil
so here H+ represents the ion from the acid...
u get it now??
-
ya fine Thanks :) :) got confused
-
hw??? I dint get it
CaO + H+(1) ---> Ca2+ + H2O(2)
H at (1) exists as an ion cos its from an acid. An acid ionizes completely or partially, meaning they split up into ions. eg.: HCl splitting into H+ and Cl-. At (2) its not H+ and OH- cos water is formed which does not ionize. I hope you get it.
-
question- how doz hydrogn combine wid O2? ca is mor reactive>
-
here we are not talking about a displacement reaction...its a neutralization reaction where water has to form by combing H and OH/O
do u get it now??
-
doubt
http://www.freeexampapers.com/FreeExamPapers.com_.php?__lo=SUdDU0UvQ2hlbWlzdHJ5L0NJRS8yMDA0IEp1bi8wNjIwX3MwNF9xcF8xLnBkZg==
Q.4.b.2 and Q.4.b.3
-
that's paper 1...
what do u mean by 4 b 2 and 4 b 3??????????
-
this is MCQ question!!
how can you expect 4b2 and 4b3???
-
@aditoxic- oh got it..din notiz dat..thankz! :)
-
sorry guyz
It is paper 3
http://www.freeexampapers.com/FreeExamPapers.com_.php?__lo=SUdDU0UvQ2hlbWlzdHJ5L0NJRS8yMDA0IEp1bi8wNjIwX3MwNF9xcF8zLnBkZg==
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4bii) first understand the q.
FeCl3 + 3NaOH --> Fe(OH)3 + 3NaCl
moles of FeCl3 = conc. * volume = 1 * 4/1000 = 0.004
MOles of NaOH = 0.004*3 = 0.012 or conc. * volume = 1 * 12/1000 (look at graph) = 0.012
when FeCl2 is used, this is the equation
FeCl2 + 2NaOH --> Fe(OH)2 + 2NaCl
Moles of FeCl2 = conc. * volume = 0.004
but here, the mole ratio is 1:2
so the moles of NaOH = 0.004 * 2 = 0.008
volume = moles/conc. = 0.008/1 = 0.008dm^3 = 8cm^3
thus, for FeCl2 --> 8cm^3 of NaOH reacts completely with FeCl2, so, the shape wud be same, only it wud become constant (parallel to x-axis) at 8cm^3 of NaOH
-
for 4biii)
the reaction
AlCl3 + 3NaOH --> Al(OH)3 + 3NaCl
Al(OH)3 is insoluble (precipitated), however, when all AlCl3 is reacted, the excess NaOH that is added reacts with Al(OH)3
Al(OH)4- ions are formed in the presence of high concentrations of hydroxide: this is soluble. Thus all the precipitate dissolves and the height of the precipitate becomes 0. for the graph, just draw a rough graph where it continues till the maximum point but falles to 0 when excess is added.
-
hope u understood. :)
-
guys whats the formula to calculate percentage yeild?
-
guys whats the formula to calculate percentage yeild?
(actual yield/theoretical yield)*100
-
enjoyed chem ;)
-
ya was actually good :) :)
-
just good ???
i thought very good :P
-
fine very very good :P :P
-
ok...!!
wahtever you say double that much good!! :P
-
increased my expectations after discussing it with a guy.
77+ :P
-
ll...discuss with me nd u'll say 80!! :P
-
hey ppl, this is urs truly, just asking u, how was chem???
please refrain from stating actual qs...
becasue we are not allowed to do so until a 24h time period??
-
chem paper 3 was fantastic...expecting 76+ / 80
-
dude aadi tera to expectations are decreasing wid each post.. :P :)
-
till now i have lost only 1 mark. so here and there count kar ke..76+ safer side!
-
dude...u are just trying to fool around...dekh ab sochle koi fayeda to hai nahi...i dont even understand why people discuss after they are out of the examination hal...cuz u cant change anythhing now....so whats the point....
nd it doesn't matter if i 68/80/76 cuz wha will matter is what u'll get on 25th jan
-
extremely generalized statement. its other's viewpoint dude, ppl like me discuss because it gives us satisfaction. simple.
-
i dont discuss because i dont remmeber the quesrtions and ans!! :P
-
satisfaction.....surely it does...to me too..but still i insist on not discussing...
-
sure, ur wish
-
By the way one last question whoever can ans it!!
it is an add. math paper
pls see my thread
i am hortly goign to post it
-
Guyz can any1 of u plz help me wid this Q.
11 For complete combustion, one molecule of an organic compound needs 8 molecules of oxygen.
What could the formula of this compound be?
A C5H11OH
B C6H9OH
C C6H11OH
D C6H12
The ans is B.C6H9OH
but hw do u derive @ this.
I had thugt it wud b D. but its wrong
Need an xplanation 4 the ans
-
okk see
its says 8 molecules of oxygen
which means a total of 16 O's in the balanced equation
now write the equation:
X + 8O2 ---> CO2 + H2O
so if we have A (C5H11OH)
then to balance for C u have to put 5 b4 CO2, which will make 10 O's so left would be 6 O's but u cannot put a 6....
hey wait...did u say u thought D as the right answer...??so which mark scheme did u check dude...the answer IS D!!!!!!
lol...just re-check man
-
@adi - D cant be the answer.
C6H12 + 8O2 --> 6CO2 + 6H2O
not balanced.
C6H9OH + 8O2 --> 6CO2 + 5H2O
now its balanced. so yea just balance and check for the answer.
-
okk see
its says 8 molecules of oxygen
which means a total of 16 O's in the balanced equation
now write the equation:
X + 8O2 ---> CO2 + H2O
so if we have A (C5H11OH)
then to balance for C u have to put 5 b4 CO2, which will make 10 O's so left would be 6 O's but u cannot put a 6....
hey wait...did u say u thought D as the right answer...??so which mark scheme did u check dude...the answer IS D!!!!!!
lol...just re-check man
i chkd the ms and the ans is still B. D isn't the ri8 ans.
-
ooooooohhhhh....m soo sorry busy and aadi...actually i did another question today similar to this one...and while explaining i recalled dt the answer was D...so didnt apply my mind there...m sorry...yeah...the answer is B
-
@adi - D cant be the answer.
C6H12 + 8O2 --> 6CO2 + 6H2O
not balanced.
C6H9OH + 8O2 --> 6CO2 + 5H2O
now its balanced. so yea just balance and check for the answer.
Thanks Aadi. I tried balancing it earlier but the cud not do it properly Thanks 4 xplainin!
@Aditoxic Thanks 4 ur help 2
-
hey thats k..no issues...
er, do u mind modifying my name there...because i'm a little wary of letting out my name in this public forum? hope u dont mind
thanks! :D
-
sry 4 da inconvience caused
-
no thats completely fine...just edit it, if ur unable to do that, inform me, i'll do it.. :)
-
Thanks Aadi. I tried balancing it earlier but the cud not do it properly Thanks 4 xplainin!
@Aditoxic Thanks 4 ur help 2
lol...dude aadi wanted his to be changed but y u changed mine...lol...bt anyways..its kk...i dont mind at all
-
thanks man! all ready for chem?
-
yeah dude!!!just finished up with some past papers...nd all set to rock it...haha....i wanna come back nd write "expecting 40/40" inthe thread tom too
bt i dont think i wud write dt b4 7-8 tom...gonna have a P-A-R-T-Y!!!!!!! :D :D :D :D
-
NJOY THE PARTY>>>>!!
-
2009 may paper 3 Question 5 b
How is it done ? They ER says:
The crucial point of the calculation is to realise that 8 cm3 of the
phosphate solution reacted with 12 cm3 of an aqueous solution of the nitrate of metal T. This can
be deduced from the graph.
Where does it say this on the graph ?
-
check the X axis of the graph...the solution contains 8 cm3 of phosphate that has reacted....the volume of the solution, after this point is constant(which implies that only 8cm3 of phosphate has reacted)
-
could u show me the steps please.
-
could u show me the steps please.
for the b) part right? like the formula of the compound?
-
like how would u do it with a proper explanation. I want to know exactly what your thinking and doing when u solve for the formula.
-
sorry for taking so long...some important calls
Anyway
Na3PO4+ nTx(NO3)y----> NaNO3+ Tnx(PO4)z
all the variables are unknown at present
U know the reaction will give sodium nitrate which has the formula NaNO3[/sub]....now u also know the volume of the product is 8cm3
the volume of sodium phosphate is 2cm3...
The mole ratio of sodium phosphate and Tnitrate is 2:3, when u try to balance for NaNO3...and u get (NO3)2. The product side has 6NaNO3
This gives us the charge on T as +2...since (NO3)2-...u know PO4 will be twice and thus T will be thrice cuz of the charges
Little weird to understand...ill put down the balanced equation, which is likely to make it easy for u to figure it out
2 Na3PO4+ 3 T(NO3)2---->6NaNO3+ T3(PO4)2
I'll try explaining again...i tried my best to explain tho...
-
so whats your final answer. what is the formula of the phosphate
-
so whats your final answer. what is the formula of the phosphate
T3(PO4)2 as given in the final equation
-
thanks nid :)
-
thanks nid :)
np
-
IGCSE Paper 3 Question 4 (b) (ii)
It says draw the new graph. How do u know where to draw the graph till. In the ms it says it should be drawn till 8cm3. How do u obtain this value and why this value ?
Help and plz explain well !!
-
IGCSE Paper 3 Question 4 (b) (ii)
It says draw the new graph. How do u know where to draw the graph till. In the ms it says it should be drawn till 8cm3. How do u obtain this value and why this value ?
Help and plz explain well !!
Hey ari!!
could you also specify the year??
-
woops... 2004 may jun
I simply dont get it at all
-
this q irritated me a lot during my IGs
heres it..
first--> remember to use mole ratio in these types of Qs
the no. of moles of hydroxide ions => moles = conc. * vol = 1 * 12/1000 (i took 12 because at 12cm^3 in the x-axis the graph becomes constant, meaning anything further is an excess) = 0.012
the no. of moles of chloride ions = 1* 4/1000 = 0.004
mole ratio : 0.004:0.012 = 1:3
---------------------
Fe2+ + 2OH- = Fe(OH)2
from the above , u know that the mole ratio is 1:2
4.0 cm3 of aqueous iron(II) chloride = 0.004 dm^3
no. of moles of chloride ions = 1 * 0.004 = 0.004 moles
let the no. of moles of hydroxide ions be 'x'
therefore, 1:2 :: 0.004 : x
x = 0.008 moles of hydroxide ions
volume = moles/conc. = 0.008/1 = 0.008dm3 = 8cm3
so the shape shud be the same but it shud go constant at 8cm^3
-
orry for taking so long...some important calls
Anyway
Na3PO4+ nTx(NO3)y----> NaNO3+ Thanks(PO4)z
all the variables are unknown at present
U know the reaction will give sodium nitrate which has the formula NaNO3[/sub]....now u also know the volume of the product is 8cm3
the volume of sodium phosphate is 2cm3...
The mole ratio of sodium phosphate and Tnitrate is 2:3, when u try to balance for NaNO3...and u get (NO3)2. The product side has 6NaNO3
This gives us the charge on T as +2...since (NO3)2-...u know PO4 will be twice and thus T will be thrice cuz of the charges
Little weird to understand...ill put down the balanced equation, which is likely to make it easy for u to figure it out
2 Na3PO4+ 3 T(NO3)2---->6NaNO3+ T3(PO4)2
I'll try explaining again...i tried my best to explain tho...
nid, im sorry i still dont get it.. :-[
-
The ansa is attatched.
Hope this helps.
-
I didn't
-
The ansa is attatched.
Hope this helps.
ansa
nice word :D
-
@dude- Maybe U r smart enough to understand....but u do not talk to any1 like that. I'm sorry but it is my duty to inform u that this is your 1st official warning
@aadi- unfortunately u haven't performed you duty well
@ Ari- If you still do not understand, lemme knw...I will try n explain it yet again :) And if there is anything that u find offensive, plz report the post and I will surely look into it....And im sorry I saw this a lil late
-
For some ppl, they need to be insulted to actually work, that is a simple question, and is fully explained even n the book both Adi and I helped Ari out, and we explained every bit, but if he still does not get it, then he is hopeless, it was a simple thing. I saw both my and Adi's explanation and we both explained all the parts. Now even after that if he does not get it, he is definitely hopeless!!!!
Secondly, the word that I have used has been used may times, no body has been given a warning for that, I do not expect to be either. Furthermore, it was in an attachment!
so, if u can stop being such a goody-two-shoes then that would be helpful. Wat u do nid is something called spoon feed ppl! That results the person being even more dependent on u as a result! wat will happen to ari when he has to rely on himself???
Sure he did not like it, but I am sure it gave him some incentive to work it out by himself and not give up!
My purposes were that of psychological change to change how he works, not to insult him!
Moreover, telling another moderator whether he has done his duty or not is a matter of perspective, as much as I respect urs, u shud respect mine!
Lastly, if u have something against me, or just that u are over-sensitive about an issue please tell me in a pm, that is what they are for!
@ari, its a joke man, and something to actually get u working! Dont take it so seriously!
-
Well if some1 takes time to understand, it doesn't mean he/she is hopeless.......
You need to be aware that not every1 here is a 98-99%.....
If there have been cases of others using that word in such circumstances, I would definitely take action...You can send me the link if you have seen the word being used to humiliate other members
If he were to do it by himself, why would he join the forum in hope of some help from others. I'm sure if he understands this, he will be able to do similar questions. But If he doesn't understand this, there will be more of the same type comin in(and when u answer each one of it for him, that's when u call it spoon-feeding) and that's when ur frustration grows...It would be better if he gets it now....
And if u change that tone of yours, I will be obliged :)
It may be simple for u....He is not the same as you
And to that psychological change u wanted to bring about...there are better ways to motivate ppl to work harder and analyse things for themselves
No personal grudges or anything if u think there is....just to make it clear...I'm just doing my job
Thanks.
And there will be no more discussion about this on this thread.
P.S. If u want to amend any of these rules, you can make a suggestion
-
WOW !!! I make one statement and we have a war going on.
I know all discussions regarding this were supposed to end with nid's post BUT lets set the record straight :
1.) The Dude 321 you have a very brusque manner of dealing with people... many people would infer that you are being an arrogant twat BUT I know that you aren't. I understand you were trying to help me and that you felt you were helping 'motivate' me.
THUS, I have a message for you. I dont need to be 'motivated' by you... I am not a 4 year old and it just so happens that I am not a HOPELESS case when it comes to chemistry or any subject as a matter of fact. I am darn good at my studies and I plan on getting all A*s
Now if u have a FUC***n* problem with that then I suggest you simply ignore my kind of people and carry on with your life...
2.) Thank you nid and aditoxic for your help in math and chem.
THE END
-
@dude- Maybe U r smart enough to understand....but u do not talk to any1 like that. I'm sorry but it is my duty to inform u that this is your 1st official warning
@aadi- unfortunately u haven't performed you duty well
@ Ari- If you still do not understand, lemme knw...I will try n explain it yet again :) And if there is anything that u find offensive, plz report the post and I will surely look into it....And im sorry I saw this a lil late
I answered his doubt and I consider that as my duty. You have just typed an extremely meaningless generalized statement.
-
Typing in arguments is not what I do, in-fact it bores me. I mean not to be arrogant and not to be rude. I have always tried to help people, many people have taken my examples and still thank me for the things that I do. Aadi being just one of them.
Now, back to business. I understand that both you me and Aadi are mods. I would kindly and sincerely like you Nid404, to understand that we do not need to be taught how to handle people! Furthermore, you do not have the right to give me a warning under any circumstances, that is the sole authority of an administrator, if you would like to consult with them, please do so or simply 'get a life'. To begin with, Aadi explained it perfectly fine, perfectly, it was the best explanation that he would get! I doubt that anyone will provide such a dedicated answer. But people totally miss the point of this, it was a joke and to some extent a motivating factor! That was its purpose!
Again I will stress, you are no more superior to me or to Aadi! Wielding an axe does not mean that other weapons are inferior, and other skills are inferior. Try to understand that the 'greatness' with which you handle your job is no more than simple oversensitiveness. Kindly refrain from making commands, I am not obligated to execute yours, and neither is Aadi.
-
to come back to the chemistry topic
how is
2H + O ----> H2O
it should be either 2H+O
or it should be
2HO
haha
silly doubt :P
-
ok lets stop it here and discuss in the lounge. this isnt the right place to be doing so. no offence, Respect :)
@vaibhav --> 4H + O2 --> 2H2O
-
to come back to the chemistry topic
how is
2H + O ----> H2O
it should be either 2H+O
or it should be
2HO
haha
silly doubt :P
Is this a serious doubt ???
Anyway there's only one atom of O, so it can'd be 2HO...:S
I still can't believe this is coming from u vaibhav
-
lol u took my doubt seriously
i got A+ in chemistry (RESPECT RESPECT :P :P)
i know it [i forgot chem not but :P]
my question is that which is the RAREST halogen on earth ??
EDIT 1:--..aww crap, i was writing this, but nid posted before i posted this .
EDIT 2 -- ... aww crap again, some weird thing going on, telling im trying to post something while my ip already posted something 5 seconds ago (that was not right ???) and after that some double post submitted ... something something while it was not posted..
lets not think about that
coming back to nid
it can be
2H + O2 ---------------> H2O
but this is wrong becasue there are 2 O's
so it shuld be
4H + O2 ---------------> 2H2O
i think im right,
-
how is
2H + O ----> H2O
it should be either 2H+O
or it should be
2HO
haha
silly doubt :P
ok i asked a wrong question
while asking i was not thinking CHEMESTRICALLY at all, and after getting replies i started thinking according to chemistry(thinking of chemistry after months :o)
-
Could some one tell me if my answers are correct to the following question.
Thanks !
PS: its in the attached doc file !
-
Typing in arguments is not what I do, in-fact it bores me. I mean not to be arrogant and not to be rude. I have always tried to help people, many people have taken my examples and still thank me for the things that I do. Aadi being just one of them.
Now, back to business. I understand that both you me and Aadi are mods. I would kindly and sincerely like you Nid404, to understand that we do not need to be taught how to handle people! Furthermore, you do not have the right to give me a warning under any circumstances, that is the sole authority of an administrator, if you would like to consult with them, please do so or simply 'get a life'. To begin with, Aadi explained it perfectly fine, perfectly, it was the best explanation that he would get! I doubt that anyone will provide such a dedicated answer. But people totally miss the point of this, it was a joke and to some extent a motivating factor! That was its purpose!
Again I will stress, you are no more superior to me or to Aadi! Wielding an axe does not mean that other weapons are inferior, and other skills are inferior. Try to understand that the 'greatness' with which you handle your job is no more than simple oversensitiveness. Kindly refrain from making commands, I am not obligated to execute yours, and neither is Aadi.
Dude look at your tone.... ::)
I never said im superior in any which way...And mods have the right to issue a warning if u don't knw.....pls read the rules.
By the way aadi is a frnd....no statement I make here is "personal".
Whatever your views are can be expressed in a better way...there is no point rediculing...cuz ur only openly showcasing everythin that u say ur not(rude, arrogant,etc..)
@aadi-evrythn 1 says to correct u is considered to be meaningless and generalized :P
{edit}- Please make statments for urself...aadi will talk to me if he has a problem...u don't need to say anything on behalf of him
-
Could some one tell me if my answers are correct to the following question.
Thanks !
PS: its in the attached doc file !
The mass of BaCO3 is incorrect
Ba=137
C=12
O=16X3
=197g
moles of BaCO3 that reacted would be 0.005(1:1 ratio)
Mass of BaCO3(pure) would be 0.005X197=0.985g
%purity=0.985/1.23 X100
=80.08%
:)
-
Thanks again Nid !!!
I messed up on calculating the mass of BaCO3 . I thought C was 12 and O was 16
:D Silly mistake ! Anyways thanks for helping !
+rep
-
QUESTION
Draw diagram 1 to show the arrangement of silicon atoms around one carbon
atom in silicon carbide. Label this diagram 1.
Draw diagram 2 to show the arrangement of carbon atoms around one silicon
atom in silicon carbide. Label this diagram 2.
ANSWER
diagram 1 four silicons around one carbon
diagram 2 four carbons around one silicon
-------------------------------------------------------------------------------------
I dont understand how this is so... the formula of Silicon Carbide is SiC with the ratio of Si:C being 4:4 hence 1:1.
How do u get the answer.... PLZ explain the UNDERLYING chemistry behind this question. What is is that u need to know to do these questions.
-
Silicon nd Carbon are both group 6 elements...valency four.
This should help u analyse the diagram.....to form an octet...they will share 4 electrons
if u still don't get it....ill explain it
-
hey guys i have searched for what i wanted on this site but haven't found wat i need
i need notes for genetic engineering, population size and human influence on the ecosystem.
they are self study topics and i want to make sure that i understand.
plz post any type of notes with these topics and thx in advance
-
No problem, I need to search for them. But this is a very good website to keep you busy:
http://www.s-cool.co.uk/gcse/biology/genes-and-genetics.html (http://www.s-cool.co.uk/gcse/biology/genes-and-genetics.html)
-
THX ;D
-
Thanks Nid for the help. Here's another question....
We all know how to draw the internal structure of an alloy. But one MS said we MUST show the presence of delocalized electrons.
How do is show this on the below diagram in a neat way ?
PS: forgive sruffy drawing
-
let me try, give me 1 min...
-
i seriosuly forgot...
but it could be like this
the minus sign represents sea of electrons
lol i really forgot :P
-
Thats more like metallic bonding....
IS BORON a semi metal ??
WHERE is NID ???
-
Thats more like metallic bonding....
IS BORON a semi metal ??
WHERE is NID ???
add small holes between metallic bonding to make it look like a alloy..
(like u see small black circles in my diag)
no boron is a non-metal..
i dont know where is nid..
answeered all ur questions :D :D :D
-
actually it will have more of a diamond like structure.
http://upload.wikimedia.org/wikipedia/commons/8/8f/Silicon-carbide-3D-balls.png (http://upload.wikimedia.org/wikipedia/commons/8/8f/Silicon-carbide-3D-balls.png)
Because Carbon and Silicon have the same bonding abilities.
Combining carbon and silicon will fore somewhat of a semi conductor. U dont need to show free electrons because there arent any.
Secondly, in semi conductors, the electrostatic force between te nucleus and the electrons are weak, and therefore, you have to go to A level stuff to explain.
The main thing they are trying to see, if u can identify that if it is tetrahedral in structure.
I hope that answers ur q.
-
is that diagram for an alloy?? or boron??
wow im back to chemistry after months and it feel good xD ;D
-
HOLD YOUR HORSES PEOPLE !!!
Everyone is getting confused with what I am asking.... so ill put it here in short:
1.) An alloy is a mixture 2 or more metals. In a diagram for an ALLOY how would you show the mobile electrons ??
2.) Is boron a metal or metalloid ? WHat is its charge ?
-
boron is a Group 13 element that has properties which are borderline between metals and non-metals (semimetallic). It is a semiconductor rather than a metallic conductor. Chemically it is closer to silicon than to aluminium, gallium, indium, and thallium.
-
Sorry. I've been away for a while
The diff colors r for the diff metals in the alloy. The positive metals ions are in the sea of electrons...similar to metallic bonding but there metals here do not bond chemically...Alloys r mixtures, not compounds
And boron is a metalloid. It exhibits a +3 charge generally. When bonding covalently it has a 5- charge(e.g. BF3)
-
yes nid is right,
wat the examiners want to see is that you have different sizes of atoms, to show there there is more than one element.
But for silicon carbide, it is as I have said.
These answers are for IGCSE and not for A level for higher. So only for IGCSE.
Hope that helps.
-
yup this is IG stuff
-
Yeah... this IG stuff. Got my exmainations in a few weeks time. The clock is ticking *tick* *tock* .... :D ;D
-
Yeah... this IG stuff. Got my exmainations in a few weeks time. The clock is ticking *tick* *tock* .... :D ;D
I have my AS in a few weeks..... :(
Igs is a piece of cake...with a cherry on the top..lol...you'll do well
Good luck! :)
-
Thanks Nid ;D
I like cherrys
-
All the best pal.
-
Question 4) e) all parts.
I dont understand how or why the temperature diff. changes.
Please explain the underlying chemistry concept. What do i need to know to do these kind of questions.
If u have time please see my other post : https://studentforums.biz/index.php/topic,6204.msg176488.html#new
-
Help ?
-
which paper?
-
2008 WINTER
-
i) When u use four grams it reduces the temp by 4 degrees. More heat is taken from the surroundings in when u add a greater mass of the substance B, reducing the temperature even further....precisely doubling the mass would cause double decrease in temp. Directly proportional
ii) when there was 30cm3 of water, heat could be taken only from that small amount of water, causing a drop of 6 degrees. More the water, the drop in temp would be lesser, as heat for the reaction is obtained from a larger volume for the same amount of solid as earlier. And since double the volume, half the temp. Inversely proportional
I explained iii) above itself
-
Thanks Nid excellent explanation. +rep
r u doing A levels ?
-
here this is awesome and has whatever you want for biology just try it out..!!
http://examstutor.com/biology/resources/studyroom/index.php
it is awesome..!! :) :) ;) ;) :D :D
-
thanks :)
Yup...
Will be giving AS this june and A2 in nov
-
http://thenightdreamer.wordpress.com/category/subjects/biology/
Check out the above link for resources, notes, power points and more on IGCSE Bio.
You could subscribe if you want.
PS: its my site
-
http://www.purchon.com/biology/revision.htm
For your population size question :: http://www.wovre.com/revision/gcse-biology-population-size/
pz :)
-
hey.. \m/ |\|!d \m/
what subjects for As level??
are you giving As and A2 together?
-
rectified my post above.
I'm givin Maths,bio,phy,chem n eng
-
Can some1 explain Question 13...Paper 1....Oct/Nov 2009....
the colour at the anode and cathodes are confusing :S....
when chlorine will turn the universdal indicator colourless at the anode then how can hydrogen change the colour of universal indicator to blu/purple...???? :S:S
i need a good explanation for this ...if some1 is kind enough.... :D :D
thnkss in advance....
-
Chlorine bleaches the indicator at the anode. When Hydrogen gas escapes at cathode, remaining solution is sodium hydroxide which is alkaline and will turn the indicator blue/purple
-
y english?
-
y english?
I beg your pardon...I didn't quite get that
-
y did u chose english at A level??
Are u first language??
Or do u just like it
or is it required for the course u wish to take at uni.
-
y did u chose english at A level??
Are u first language??
Or do u just like it
or is it required for the course u wish to take at uni.
Yup first language. It's compulsory :-X
-
i am english first lang as well
but i did not have to take it at a level
and i got an astar in it as well
is it a skool policy??
-
i am english first lang as well
but i did not have to take it at a level
and i got an astar in it as well
is it a skool policy??
its not just a school policy, its a policy for all the schools offering a level in india. a level is not offered to a student in india unless they take english
-
yaa something like that....u go to any school in india, english is a must
-
OHk...bio n chem help available here guys...
When ull make new threads i tend to miss it somehow...unless someone else posts and then I notice
So guys, go ahead with your questions here...I'll try my best to answer asap
-
Yeah and Nid any other old chemistry and bio threads doubts, you can merge them to this thread.
-
Yeah that'll be good...I'll look for them :)
-
Describe Germanium (IV) Oxide structure...
I say: It has a tetrahedral structure with one Germanium atom covalently bonded to 4 Oxygen atoms. Also Each Oxygen atom is covalently bonded to 2 Germanium atoms.
Am i correct ?
-
perfect.
that would score full marks.
-
a) What would be the product at the anode if MOLTEN CuSO4 were electrolysed with GRAPHITE electrodes.
b) If you add bromine water to but-2-ene will the product be 2,3-dibromobutane ??
c) Describe, by means of a simple diagram, the lattice structure of an ionic compound,
such as caesium chloride. Could u please draw the diagram and upload it here ?!
-
srry m late
a) I'm a little unsure...will give a def ans in a while
b) yes right
c)
(http://www.drbateman.net/asa2sums/sum1.3/image17.gif)
-
Question 5 (d) whats your diagram look like ?please upload here.
-
???
-
srry I almost forgot
gimme a few min...I'll get back
-
Here it is
-
Stay online for a few moments
-
https://studentforums.biz/index.php/topic,6394.0.html
Are you sure about the structure for Ca Cl ?? Why do all the ions connect to one in the middle ?
-
It's not converging at the centre...the bold lines are just showing the 3-D structure
the connecting lines are not in bold...
-
how do i revise for biology , it's such a huge syllabus?!!?! ...oh and can u tell me where can i find the methods for the experiments in paper 6 chemistry ?
thx in advance
-
These are bio audio revison files:
http://cid-9132d87007ea7520.skydrive.live.com/browse.aspx/.Public/Biology%20Podcasts%20-%20Audio%20Revision?uc=2
These are revison powerpoints/pdf files:
http://thenightdreamer.wordpress.com/category/subjects/biology/
By the way The Nightdreamer Inc. is my website !!
-
Yes, indeed, of all the 3 sciences, bio has a vast portion....
You may have a good revision guide for igcse....http://www.amazon.co.uk/IGCSE-Study-Guide-Biology-Guides/dp/071957904X
It's excellent
But remember to read your textbook...never leave that out....
And if u don't understand a concept on reading, look online for help....some good diagrams and videos might help.....if u still have problems, post them here ;)
-
thx alot :) ....but u didn't answer my question about the chemistry experiments
-
hmm....overlooked that...srry
Solve as many past papers as you can...
http://www.collinseducation.com/TitlesListing/pages/productshow.aspx?Level1=Secondary&ProductId=35339
A good book with a lot of practical examples....
try getting an e-book cause it is quite expensive....try freeetextbooks.com
-
can u pls tell me the test for carbonates?
Thanks...
-
well, wen carboantes react with acids, they give out CO2.
Thus, you will be able to test for the CO2 using limewater.
So simply collect tha gas given off in the reaction between a carbonate and an acid.
And then test the gas given off using limewater. Limewater will become cloudy.
-
got it
Thanks a lot
-
one more question
are group 2 carbonates soluble?
if any1 could pls give me a solubility guide, it would be really helpful; im doing igcse chem
Thanks...
-
The solubility of carbonates decrease down the group.
Thats all you need to know for now, as for particular carbonates, simply search the web to see whether they are soluble or not.
-
ok great
Thanks
-
any tips for revsion....seeing as our exams are a month away??
-
hmm....
Past papers is the key....but learn ur base concepts well
Any problems, ur more than welcome to post here
-
yes....
do past-papers a lot
and if u have any problems
be sure to post them here: https://studentforums.biz/index.php/topic,4425.495.html
i can help u pretty much with all subjects
-
I have a doubt in Biology paper 6 O/N/07, in Q1 (b) (ii) it is written in da mark scheme : agitate the same, what do u mean by this. Can anyone tell me what is a buffer?
Finally, can u write a model answer for it, i just don't get the question ???? Thank u in advance! :D
-
I have a doubt in Biology paper 6 O/N/07, in Q1 (b) (ii) it is written in da mark scheme : agitate the same, what do u mean by this. Can anyone tell me what is a buffer?
Finally, can u write a model answer for it, i just don't get the question ???? Thank u in advance! :D
the point u mentioned is followed by increase in range of pH tested....this means u carry out the same procedure to obtain the desired result for the new temperatures...
Buffer is an ionic compound that resists change in it's pH. So, when u use a buffer, u ensure that there is no change in pH...thereby maintaining the desired pH(making the results more reliable)
-
Thank You ;D
-
hey cn any one hlp me understand the calculations chemistry (olvl)
-
hey cn any one hlp me understand the calculations chemistry (olvl)
Be specific. Post a question that you dont understand and I ll help you.
-
Be specific. Post a question that you dont understand and I ll help you.
the solving confuse me when i solve a question i get confused which rule to use
-
the solving confuse me when i solve a question i get confused which rule to use
Okay for gases use the following:
moles of gas = volume of gas/24000 NOTE: use 24000 when volume in cm^3 and use 24 instead when volume is in 24 dm^3
For liquids use::
moles of liquid= (volume of liquid in cm^3 * concentration in mol/dm^3) / 1000
For solid use:
moles = mass in grams/mass number of element NOTE: if its a solid compound then add up the mass nos. of each element
-
Thank You ari :)
-
An aqueous solution contains barium iodide.
It is possible to obtain a solution that contains Ba2+(aq) but no I–(aq) by adding ……1…… until no
more ……2…… precipitate forms.
Which words correctly complete gaps 1 and 2?
1 2
A) aqueous lead(II) nitrate white
B) aqueous lead(II) nitrate yellow
C) dilute sulphuric acid white
D) dilute sulphuric acid yellow
FROM WINTER 2008 Paper 1
------------------------------------------------------------------------------------------------------------------------------------
I don't understand how the answer could be B. Because if BaI2 reacts with Lead Nitrate u get Lead Iodide (hence the presence of I ions) and u get Barium Nitrate.
Actually in both reactions you would get I ions and Barium ions.
HELP !
-
They want only Ba2+ ions in the solution....which means they want iodide to ppt off....
so to do that, you add lead nitrate...lead iodide precipitates off and the solution contains BaNO3..
Gettin it?
-
I would just like to take this moment to say...
I LOVE CHEMISTRY !
-
Okay for gases use the following:
moles of gas = volume of gas/24000 NOTE: use 24000 when volume in cm^3 and use 24 instead when volume is in 24 dm^3
For liquids use::
moles of liquid= (volume of liquid in cm^3 * concentration in mol/dm^3) / 1000
For solid use:
moles = mass in grams/mass number of element NOTE: if its a solid compound then add up the mass nos. of each element
Thank You ur the best
-
An aqueous solution contains barium iodide.
It is possible to obtain a solution that contains Ba2+(aq) but no I–(aq) by adding ……1…… until no
more ……2…… precipitate forms.
Which words correctly complete gaps 1 and 2?
1 2
A) aqueous lead(II) nitrate white
B) aqueous lead(II) nitrate yellow
C) dilute sulphuric acid white
D) dilute sulphuric acid yellow
FROM WINTER 2008 Paper 1
------------------------------------------------------------------------------------------------------------------------------------
I don't understand how the answer could be B. Because if BaI2 reacts with Lead Nitrate u get Lead Iodide (hence the presence of I ions) and u get Barium Nitrate.
Actually in both reactions you would get I ions and Barium ions.
HELP !
its B because its test for anion and cation he is testing for iodine tht form yellow ppt whn (acidified leadnitrate) is added got it?XD
-
ok the ORGANIC i understand the alkane and alkenes part when it comes to he next i cnt study these u hv notes for the organic (u can skip alkanes and alkenes)
-
Be a a lil specific plz....
cuz i don't remember what comes after that...I gave my igz a yr back.....syllabus not very fresh in my memory...
Thanks
-
alcohols,carboxylic acid,esters,polymerization
-
http://www.docbrown.info/
nice site....verything pertaining to organic for igz
-
Thank You man ur the best
-
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_3.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_3.pdf)
Question number: 9) b)
I'm good in chemistery but my biggest nightmare is statiochemtry, so plz can u explain how to do in a baby-simple way :D ;D
thx ;)
-
SO write the equation out :
Al4C3 + H2O = Al(OH)3 + CH4 We know that H2O was in excess so ignore it for now and compare the moles of each substance
l l l
l l l
0.03 moles 0.12 moles 0.09 moles
then look at the ratio of moles i.e. 0.03:0.12 (which can be simplified to 1:4) and 0.03:0.09 (which can be simplified to 1:3)
Thus u now have 1Al4C3 + ?H20 = 4Al(OH)3 + 3CH4
Now compare the no. of atoms as per the new balancing an we just need to add a 12 before H20 to balance everything out. DONE !!
-
Okay Nid need your help again.
2008 Summer Paper 6 Question 4 e ii
I think the MS is wrong. If you use a greater volume of a solution shouldnt the conc. of that particular solution be LOWER ?
I keep getting questions regarding changes in concentration & volume wrong. Is there a formula/principle linking these two. Is there anything in your AS/A level textbook that can help me out with this stuff.
-
Twice as much soln of KMNO4 ws used for A ws as compared with B.
More the amount of KMNO4 required to complete the react means more no of moles of the substance(that is more conc )
More of it required for A, so A is more concentrated...
Get this right....conc of KMNO4 used is same for both....so the greater the volume of KMNO4 used, greater the conc of te conc of the substance
-
Thanks I got it !
But is there any principle/formula for all of this. Even if it a level stuff I am willing to learn and understand it.
-
Actually ari, it's more like logic
see consider this
A+ KMNO4
25cm3 + 26cm3
conc x conc z
B + KMNO4
25cm3 + 13cm3
conc y conc z
no of moles of a KMNO4 in 13cm3= vol X con
= 13z
no of moles of KMNO4 in 26cm3= 26 Xconc
=26z
more no of moles in 26cm3
implies more no of moles of A 26z> 13z of B
vol of A n B are same....conc=mol/vol
therefore conc A > conc B
-
If you still don't get it....ill use numericals...
lemme knw
-
Hmmmm... nice analogy.
But this is nt my real problem.
Okay heres an example.
If 50 cm3 of HCl are added to 1 g of CaO we get a temp change of +1
Now if we double the volume of acid how is the temp change affected. I know it would go down but WHY ??
Another example.
If 50 cm3 of HCl 1 mol/dm3 conc. are added to 1 g of CaCO3. We get a max. CO2 volume of 60 cm3
If 50 cm3 of HCl 0.5 mol/dm3 conc. are added to 1 g of CaCO3. We get a max CO2 volume of 30 cm3 BUT WHY ???
-
I'll be back after dinner.....I'll explain the concept
-
I'll be back after dinner.....I'll explain the concept
LOL even I m having dinner now. Take your time...
-
to ur 1st question
The heat given out would be distributed in a larger volume of acid....so temp rise will be less...
H=mcdt (h=heat given out/absorbed, c=sp heat capacity, dt=change in temp)
H will be the same
m will increase.....c is constant....so dt will decrease
ya?
-
Another example.
If 50 cm3 of HCl 1 mol/dm3 conc. are added to 1 g of CaCO3. We get a max. CO2 volume of 60 cm3
If 50 cm3 of HCl 0.5 mol/dm3 conc. are added to 1 g of CaCO3. We get a max CO2 volume of 30 cm3 BUT WHY ???
ok let's write down the equation
CaCO3 + 2HCl---> CaCl2 + H2O+ CO2
look at the ratio
HCl : CO2
2 :1
no of moles of HCl in case 1= 0.05---> 0.025 moles of CO2=60cm3
no of moles of HCl in case 2= 0.025--->0.0125 moles of CO2= 30cm3
got it?
-
Got it Nid.
Thanks for taking the time out to help me... again XD
+rep
-
no prob...
I like it :)
-
no prob...
I like it :)
Chemistry rocks....
-
guys in MS whn it says ref. wht it means??? refer or reference???
-
Hi, iwant 2 ask a few Qs
1. what is de main function of porus membrane in a membrane cell (electrolysis)
2. Is this a redox or displacement reaction....Zn + CuSO4 -- ZnSO4 +Cu ?
3. How does afuel cell worf (hydrogen nd O2)?
-
Hi, iwant 2 ask a few Qs
1. what is de main function of porus membrane in a membrane cell (electrolysis)
2. Is this a redox or displacement reaction....Zn + CuSO4 -- ZnSO4 +Cu ?
3. How does afuel cell worf (hydrogen nd O2)?
1.) I think your refering to the electrolysis of conc. NaCl. The membrane allows Na+ ions to move to the right of the cell to meet OH- ions
2.) Its both. In an exam you give any as your answer. The Zn displaces Cu from its salt at the same time losing 2 electrons to Cu2+ to form Cu metal.
3.) ill be back...
-
guys in MS whn it says ref. wht it means??? refer or reference???
reference..
-
Quick question:
what is the effect of pouring a strong alkali on to a metal ?
-
product would be metal hydroxide and hydrogen
not always if the metal in the alkali is more reactive, there will be no reaction
-
Three reactions used in the manufacture of sulphuric acid are shown.
S + O2 -> SO2
2SO2 + O2 -> 2SO3
SO3 + H2O -> H2SO4
Which of these reactions are redox reactions?
I dont understand how it is 1 and 2 only. Where is the reduction and oxidation going on each equation ?
-
Three reactions used in the manufacture of sulphuric acid are shown.
S + O2 -> SO2
2SO2 + O2 -> 2SO3
SO3 + H2O -> H2SO4
Which of these reactions are redox reactions?
I dont understand how it is 1 and 2 only. Where is the reduction and oxidation going on each equation ?
Alright..here's the deal..First and foremost, you have to calculate the oxidation state of the Sulpher species..
1) It goes from 0 in Sulpher (natural element) to +4 i sulpher dioxide...
SO^2...X+(2x-2)=0
and so X=+4.....sulpher is oxidzed
2) It goes from +4 in sulpher dioxide (again) to +6 in sulpher trioxide..
SO^3...X+(-2x3)=0
X=+6..sulpher is oxididzed again
3) No redox reaction
It goes from +6 in sulpher trioxide to +6 in sulphuric acid...
H^2SO^4.....
The H ion is +1..and since there are 2 such ions...the sulphate ion SO^4 must have a charge of -2..
X+(4x-2)=-2
X=+6
Hope that helped..
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Excellent explanation. I completely understood.
+rep :)
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thanks amr
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Another quickie..
would Gold react with conc. H2SO4 ?? I think so.
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Another quickie..
would Gold react with conc. H2SO4 ?? I think so.
No it would not...Any metal below copper in the reactivity series, including copper itself, would not react with an acid as they are extremely nonreactive...and it doesnt matter whether the acid is concentrated or not....However, dont confuse metals with their oxides..Copper oxide can react with acids..
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Excellent explanation. I completely understood.
+rep :)
glad i helped :)
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thanks amr
anytime...Sorry for answering the question ;D..i know u rock at chemistry..but i just wanted to help ;D
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hey nid
do u have a good resource for the topic of The Mole Concept.
these qs in the exam drive me crazy.
Also The equilibrium concept
thx in advance
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anytime...Sorry for answering the question ;D..i know u rock at chemistry..but i just wanted to help ;D
lol...I need help...I have to many questions to answer.. Happy to get a helping hand :D
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hey nid
do u have a good resource for the topic of The Mole Concept.
these qs in the exam drive me crazy.
Also The equilibrium concept
thx in advance
check the attachment :)
This should be enough
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1.) I think your refering to the electrolysis of conc. NaCl. The membrane allows Na+ ions to move to the right of the cell to meet OH- ions
2.) Its both. In an exam you give any as your answer. The Zn displaces Cu from its salt at the same time losing 2 electrons to Cu2+ to form Cu metal.
3.) ill be back...
Why doesnt the OH ions move towards anode while da Na ions move 2ward cathode.......How does da membrane only allows Na 2 pass thru..?
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Why doesnt the OH ions move towards anode while da Na ions move 2ward cathode.......How does da membrane only allows Na 2 pass thru..?
membrane allow small particles and ions only which is hte NA ions thts all
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Hi, iwant 2 ask a few Qs
1. what is de main function of porus membrane in a membrane cell (electrolysis)
2. Is this a redox or displacement reaction....Zn + CuSO4 -- ZnSO4 +Cu ?
3. How does afuel cell worf (hydrogen nd O2)?
3)the combustion of hydrogen(by oxygen) produce energy +water
2H2-4e=4H+ (oxidation)
4H+ + O2 + 4e = 2h2o (reduction)
so the overall is
2h2+ o2 = 2H2O
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needhelp plzzz on bio nervous system espicially source of relay nuerons and all the nuerons
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needhelp plzzz on bio nervous system espicially source of relay nuerons and all the nuerons
check dr.mervat u ll find it khaled
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http://www.medtropolis.com/VBody.asp
check this khaled
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In the Daniel Cell there is an electrolyte of Copper Sulphate (blue in colour ??).
When the cell starts up does the blue colour of the electrolyte fade until it becomes colourless and the cell stops working ?
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In the Daniel Cell there is an electrolyte of Copper Sulphate (blue in colour ??).
When the cell starts up does the blue colour of the electrolyte fade until it becomes colourless and the cell stops working ?
what are the electrodes??? the answer depends on this
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The usual man, zinc and copper.
SO does the electrolyte's blue colour fade ?
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if electrode is copper then it won't because cu ions tht lost from the solution to cathode replaced with one's from anode till anode all dissolve thn reaction stop
am not sure if the electrode is zinc but i guess the same
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Actually never mind the above doubt. I made a mistake... i figured it out myself.
Heres another one...
How would you describe a liquid alkane ? Does it have a particular smell or any features that you could observe directly ? I am talkin with reference to the analysis part of Paper 6.
When lead nitrate and potassium iodide are reacted what is the name of reaction that takes place ? Is it precipitation or double displacement ?
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Actually never mind the above doubt. I made a mistake... i figured it out myself.
Heres another one...
How would you describe a liquid alkane ? Does it have a particular smell or any features that you could observe directly ? I am talkin with reference to the analysis part of Paper 6.
When lead nitrate and potassium iodide are reacted what is the name of reaction that takes place ? Is it precipitation or double displacement ?
precipitation i guess lead iodide is yellow ppt
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I thought so too, but this kharban MS from 1992 said double displacememnt. Its not even the real MS !!
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The term double diplacement can also be used for a precipitation reaction since they are exchanged.
For the above reaction:
Lead nitrate + potassium iodide=> lead iodide + potassium nitrate
So u see here potassium took the nitrate and lead took the iodide
It is a precipitation reaction since lead iodide is insoluble just as everyone said.
Overall we can say any precipitation reaction is also a double displacement!
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Actually never mind the above doubt. I made a mistake... i figured it out myself.
Heres another one...
How would you describe a liquid alkane ? Does it have a particular smell or any features that you could observe directly ? I am talkin with reference to the analysis part of Paper 6.
When lead nitrate and potassium iodide are reacted what is the name of reaction that takes place ? Is it precipitation or double displacement ?
here's what i know:
alkanes r colourless
are less dense than water (will float in water)
have low melting and boiling points
insoluble in water
hope it helps
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I know the analysis question about the alkanes. It said in one paper 6 that substance F I guess smells like petrol what can you conclude of the nature of F?
This is how I understand it, since all fractions of petroleum are alkanes and petrol is a fraction of petroleum therefore petrol is an alkane and hence this substance smells like petrol, it would definitely be an organic substance most probably an alkane!
Hope this helped!
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I know the analysis question about the alkanes. It said in one paper 6 that substance F I guess smells like petrol what can you conclude of the nature of F?
This is how I understand it, since all fractions of petroleum are alkanes and petrol is a fraction of petroleum therefore petrol is an alkane and hence this substance smells like petrol, it would definitely be an organic substance most probably an alkane!
Hope this helped!
Thanks. I remember that question too, thats why I was asking if there were any other things that could be used to identify them.
Heres anothery query:
SO3 + H2O -> H2SO4 This reaction only involves reduction, right ? No oxidation and hence its not a redox reaction ?
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Thanks. I remember that question too, thats why I was asking if there were any other things that could be used to identify them.
Heres anothery query:
SO3 + H2O -> H2SO4 This reaction only involves reduction, right ? No oxidation and hence its not a redox reaction ?
No..to begin with..you must know that it is not possible to have reduction without oxidation, or vice versa...thats y it is called REDOX..
In this reaction, there is no reduction or oxidation..and so its not a redox
SO^3.....X+(6x-2)=0
so X=+6
H^2SO^4 :
SO^4 has a charge of -2.
so X+(4x-2)=-2
again X=+6..
therefor no reduc, no oxid, no redox..
hope that helped
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Yeah... i see.
Thanks again man ! :)
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would some1 plz care to explain the following from the bio syllabus:
- explain enzyme action in terms of the ‘lock
and key’ model
- outline the use of microorganisms and
fermenters to manufacture the antibiotic
penicillin and enzymes for use in biological
washing powders
- describe the role of the fungus Penicillium in
the production of antibiotic penicillin
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Yeah... i see.
Thanks again man ! :)
any time :) dear mate
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would some1 plz care to explain the following from the bio syllabus:
- explain enzyme action in terms of the ‘lock
and key’ model
- outline the use of microorganisms and
fermenters to manufacture the antibiotic
penicillin and enzymes for use in biological
washing powders
- describe the role of the fungus Penicillium in
the production of antibiotic penicillin
1) each enzyme has its own substrate tht is complementary to its active site (like key and lock)
2)enzyme in washing powder:
a)protease use for protean stains and lipase for fat and greasy stains
b) put micro organism (bacteria or fungi) in fermenter with optimum conditions to reproduce (asexual):
1)temp.( by cold water or steam)
2)sugar --> energy
3)ammonia ---> nitrogen for protean
4)air
5)salt --> help metabolic reaction
6)light for algae i used
if u need the fungi it is filtered after this process (residue)
if u need the enzyme it will be in the filtrate
the penicillin is made from Penicillium
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CnH2n+2(g) + (1.5n+0.5)O2(g) nCO2(g) + (n+1)H2O(g)
Thats the formula to balance the equation for the burning of an ALKANE
Whats the quick method for ALCOHOL and ALKENE
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CnH2n+2(g) + (1.5n+0.5)O2(g) nCO2(g) + (n+1)H2O(g)
Thats the formula to balance the equation for the burning of an ALKANE
Whats the quick method for ALCOHOL and ALKENE
My advice is to never use such equations..u cud get caught if he asks for carbon monoxide instead of dioxide..use ur calculatoions to balance..not formulae..
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dude can you tell me please wat is meant by no intermediates formed (inheritance) biology and also solvemay june 2007 quetion three fulland post please
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GUYS wht are the essential elements in fertilizers (chemistry) potassium,......,..... wht are others??
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GUYS wht are the essential elements in fertilizers (chemistry) potassium,......,..... wht are others??
potassium, nitrogen, phosphorous
N P K fertilizers
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potassium, nitrogen, phosphorous
N P K fertilizers
Thank You
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thanks for all those who helped :)...i've been a lil occupied :(
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ppl i need someone to tell me
1. what is an equilibrium mixture? :-\
2.what is meant by shifting the equilibrium position to the right/left? :-\
3. The effect of temperature,pressure,catalyst on exo and on endo thermic reactions? and why? :-\
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I'm going to hazard a guess because I haven't done this for a while... :)
1. An equilibrium is when a reversible reaction is balanced and the overall chemical concentrations and activity of both the reactants and the products has no overall net change. In an equilibrium, a forward and backward reaction occurs.
2. (Just so you know, in a equilibrium reaction, you can either go from turning the reactants into products or you can go backwards by changing the products back into the reactants.)
If you shift the equilibrium position to the right, then you are producing more product by forcing the reaction to go in the direction of the arrow facing right.
If you shift the equilibrium position to the left, then you are turning more of the product back into the reactant(s) by forcing the reaction to go in the direction of the arrow facing left.
3. In an equilibrium, one way the reaction is going to be exothermic and the other way it will be endothermic. Thus, when you increase the temperature, the reaction will want to lower the temperature and therefore the endothermic reaction will occur more to counterbalance this. Therefore, if you decrease the temperature, the exothermic reaction will occur more.
If you increase the pressure, the equilibrium system will shift so the least number of gas molecules are formed because the more gas molecules there are, the more collisions there are because these collisions and the presence of gas molecules are what cause the pressure to increase. Therefore, a decrease in pressure will force the reaction in the direction of more number of gas molecules.
A catalyst increases the rate of reaction but this would not effect the equilibrium itself so it will remain balanced.
I hope this helps and actually makes sense. I also hope that it's right :D
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thanx angel :)
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Not a problem ;D
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thank u angel and yes it did help
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Thanks angel :)
Ok...I found this ppt off the net....make good use of it
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I have a doubt ??? in Chemistry which is about this question:
The formula of an acid is either of the type HY or H2Y.How could u find out which one is correct by using aqueous solutions of acids and alkalis. Assume that both solutions have da same concentration of 0.1 mol/dm3.
I understand that we need to carry out titration and find out the volume of acid used and that if the volume of acid is same as da alkali then it is HY but wat I don't understand is why if it is H2Y then it is twice da alkali (mark scheme) I thought it is HALF!PLZ explain :-\
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I have a doubt ??? in Chemistry which is about this question:
The formula of an acid is either of the type HY or H2Y.How could u find out which one is correct by using aqueous solutions of acids and alkalis. Assume that both solutions have da same concentration of 0.1 mol/dm3.
I understand that we need to carry out titration and find out the volume of acid used and that if the volume of acid is same as da alkali then it is HY but wat I don't understand is why if it is H2Y then it is twice da alkali (mark scheme) I thought it is HALF!PLZ explain :-\
Give me a sample question...it'll be easier for me to explain
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Ok, If for example we used 25 cm3 of NaOH with concentration 0.1 mol/dm3 and it was neutralised by H2SO4 of concentration of 0.1 mol/dm3 then what is the volume of H2SO4 needed?
Repeat this with HCl having same concentration and also find its volume!!!!!!!
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Ok, If for example we used 25 cm3 of NaOH with concentration 0.1 mol/dm3 and it was neutralised by H2SO4 of concentration of 0.1 mol/dm3 then what is the volume of H2SO4 needed?
Repeat this with HCl having same concentration and also find its volume!!!!!!!
This is pure stoichiometry
Always write down equations to help you
2NaOH + H2SO4----> Na2SO4 + 2H2O
check the ratio of NaOH to H2SO4
2:1
Conc= mol/vol
moles=25/1000 X 0.1
=2.5X10-3
no of moles of H2SO4 = 2.5X10-3/ 2
=1.25X10sub]-3[/sub]
conc of H2SO4 used was also 0.1mol/dm3
vol of H2SO4[/sub= moles/conc= 1.25X10sub]-3/ 0.1=0.0125dm3=12.5cm3
frankly u don't have to do this....when u see the conc is the same....mole ratio=vol ratio
Second part
NaOH+ HCl= NaCl+H2O
Ratio is 1:1
so like i said don't bother...conc is same...vol of HCl used is 25cm3
If u further explanation...do ask
Hope this helps
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NaOH H2SO4
Conc - 0.1mol/dm^3 Conc - 0.1mol/dm^3
Vol - 25cm^3 Vol - ?
2NaOH + H2SO4 --> Na2SO4 + 2H2O
Ratio - 2:1
No. Of Moles of NaOH - 25/1000 * 0.1 = 0.0025
There4 No. of Moles of H2SO4 = 0.00125
0.00125 = VOl. * 0.1
Vol = 0.00125/0.1 = 0.0125dm^3 = 12.5cm^3.
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http://www.webchem.net/notes/Periodicity/titration_calcs.htm
Check this for examples and Revision.
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Thank you very much....!
Now, sorry but I have another one :
Usually IGCSE questions ask to draw the structure of Nylon or Terylene so do we draw boxes and the Linkage like NHCO and COO or we have to know what the boxes represent?
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you can't know what the boxes represent until they tell you the name of the monomer...
so if they say simply to draw the structure, you just show the link and the box...but for polyamides, remember the boxes will be different...they have different monomer units
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A question related to this, wat are da differences between Fats and synthetic Polyesters and Proteins and Polyamides.
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Wat if they have have given us the names of monomers like benzene-1,4-dicarboxylic acid and ethane-1,2-diol, then wat do we do?
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Fats are natural esters....
synthesized polyesters are ones manufactured artificially
Proteins are natural polyamides
Polyamide is polymer of amide monomers linked by peptide bonds
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Wat if they have have given us the names of monomers like benzene-1,4-dicarboxylic acid and ethane-1,2-diol, then wat do we do?
wait...I'll draw the polymer..stay for a while
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Here u go
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Thanks Nid.. :)
+ rep.
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Thank you :-*
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does any1 have a diagram or a flash file that explains and shows ultrafiltration and reabsorption in the kidney for ig sylabus only.
thx in advance :)
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Blood is got to the kidney via renal artery. The renal artery divides into a great number of arterioles and capillaries, mostly in the cortex. Each arteriole leads to a glomerulus. The pressure in the glomerulus causes part of the blood plasma to leak the capillary walls. The RBC's and proteins in plasma r too big to pass out. The fluid that moves out contains mainly water with dissolved salts, urea, glucose and uric acid. The process by which the fluid is filtered out of the blood by the glomerulus is called ultrafiltration. The filtrate from the glomeruls collects in the renal capsule and trickles down the renal tubule. As it does so, the capillaries which surround it absorb the substance the body needs. All the glucose is absorbed, with much of the water(depends on the state of hydration). The some salts r taken back to keep the correct con in the blood. This process of taking back the required substances is called selective reabsorption.
Substances that r not needed pass further down to the collecting duct into the pelvis of the kidney. From here the fluid, now called urine, passes down the ureter to the bladder.
Nephron- A single glomerulus with its renal artery, renal tubule and blood capillaries
visit the site for a good animation http://www.biologymad.com/resources/kidney.swf (http://www.biologymad.com/resources/kidney.swf)
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Thanks nid ;D
+ rep
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What will happen if electricity was passed through:
(a) Sugar solution
(b)ethanol solution
I know that sugar and ethanol are NON electrolytes but isn't a sloution means there is water so H+ and OH- will be there? So will H2 and O2 be produced or not???????
Thank u in advance
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no because H+ and OH- ions will only be conducted when the solution is aqueous.
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hey nid 404 can ua answer that y the urine sample of preganant women is taken???
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hey nid 404 can ua answer that y the urine sample of preganant women is taken???
HCG(human chorionic gonadotrophin)..this is present in the urine of pregnant women..so testing for HCG in urine determines whether a woman is pregnant or not
You want to know more?
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Just a clarification: After the blood plasma leak through the capillary walls, the RBCs and proteins pass through the Henle's loop where absorption of glucose and other substances are absorbed? And the reabsorption of water happens in the Henle's loop or just before the collecting duct?
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loop of henle
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Can someone please help me with the nitrogen cycle?
I came across this question in one of the papers, don't remember exactly which one, but for 4 marks we had to explain the breakdown of amino acids in the liver. Can you please give me the answer to that
thanks in advance!
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hey nid 404 can ua answer that y the urine sample of preganant women is taken???
to test the ESTROGEN AND PROGESTERONE LEVEL IN THE URINE
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Can someone please help me with the nitrogen cycle?
I came across this question in one of the papers, don't remember exactly which one, but for 4 marks we had to explain the breakdown of amino acids in the liver. Can you please give me the answer to that
thanks in advance!
post the question...i won't know how to phrase my answer
anyway check this http://www.nicksnowden.net/Module_3_pages/nitrogen_cycle.htm
@DEGO-they test for HCG
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whats loop of henle?
i hv never heard of it...........is it in igcse syllabus?
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The loop of Henle is a u shaped part of the tubule that mainly re-absorbs sodium chloride and water.
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post the question...i won't know how to phrase my answer
anyway check this http://www.nicksnowden.net/Module_3_pages/nitrogen_cycle.htm
@DEGO-they test for HCG
the question is describe what happens to amino acids inside liver cells.
is the answer the liver sends the amino acids in the blood stream to be distributed to all parts of the body. Excess amino acids are stored in the body after the ammonia from them is removed and converted into urea which is sent by the liver to the kidneys to be excreted.
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the question is describe what happens to amino acids inside liver cells.
is the answer the liver sends the amino acids in the blood stream to be distributed to all parts of the body. Excess amino acids are stored in the body after the ammonia from them is removed and converted into urea which is sent by the liver to the kidneys to be excreted.
nope , actually the answer is abit longer and diff ...
1.excess amino acids r deaminated"broken down" by liver to form ammonia , ammonia combines with CO2 to from urea .
2.liver maintains an amino acid pool
3.amino acids r changed into plasma proteins and transported by blood to al body parts , and some amino acids change into liver protien to be used by the liver.
hope i helped
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to test the ESTROGEN AND PROGESTERONE LEVEL IN THE URINE
srry but i don't get it ! ....can someone explain to me y doctors take urine sample from pregnant ladies ?
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i kno i posted alot today :P ... anyways i am just wondering where can i find the marking scheme of the old years in chemistry IGCSE paper 1 .
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srry but i don't get it ! ....can someone explain to me y doctors take urine sample from pregnant ladies ?
HCG(Human chorionic Gonadotrophin) is present in a pregnant woman's urine...they take the urine sample to test for HCG.
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Okies people.
Why WOULDN'T you use Universal Indicator in a titration experiment. Instead why WOULD you use methyl orange ?
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While titrating, you can't use Universal indicator because it changes its colour gradually, gives diff colors for diff pH. You won't know when the reaction is complete...
While methyl orange or phenolphthalein are used instead because they give a sudden color change. It is better to for us to see the end point
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While titrating, you can't use Universal indicator because it changes its colour gradually, gives diff colors for diff pH. You won't know when the reaction is complete...
While methyl orange or phenolphthalein are used instead because they give a sudden color change. It is better to for us to see the end point
Ahhhhh.... Thanks nid. My lack of practical experience worries me. Next year I am gonna kill the teacher if we dont do proper experiments.
Kef halak ana akh means how are you my brother ;)
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Ahhhhh.... Thanks nid. My lack of practical experience worries me. Next year I am gonna kill the teacher if we dont do proper experiments.
Kef halak ana akh means how are you my brother ;)
i know kef halak
ana bikhair (i knw i spelt it wrong but i knw :P ) Ahmadullilah (i know this is spelt wrong too :P )
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Mumtaaz ! Means excellent.
Au Revoir ! (Can you guess what this means :P)
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thts french dodo ! :P
You know more arabic than you know hindi....laanat hain ! :P
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hey nid??? explain why antibiotics kill bacteria but not
viruses and describe the medicinal use of antibiotics for the
treatment of bacterial infection
-
hey nid??? explain why antibiotics kill bacteria but not
viruses and describe the medicinal use of antibiotics for the
treatment of bacterial infection
What antibiotics do is they prevent formation of bacterial cell wall, thus leading to their death
Antibiotics target only bacterial function and structure and so have no effect on virus'
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20 cm^3 of 1 mol/dm^3 of NaOH was titrated with a certain amount of H2SO4 of 1 mol/dm^3
The H2SO4 was added in portions. Each consecutive portion caused the temperature to rise (initial starting temp. was 25 degress):
Addition of 5 cm3 Addition of 15 cm3 Addition of 25 cm3 35 cm3
1st portion 2nd 3rd 4th
27 degrees 31 32 30
The experiment is repeated with 20 cm^3 of 0.5 mol/dm^3 of NaOH and H2SO4 of 0.5 mol/dm^3
Suggest what volume of H2SO4 would produce the highest temp. ?
---------------------------------------------------------------------------------------------------------------------------------------
No MS available, but I think its 50 cm3
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Just by looking it gives me 12.5cm3
I'll work it out still...10-15min
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Just by looking it gives me 12.5cm3
I'll work it out still...10-15min
There are fewer moles of acid in the NEW experiment. Doesnt that mean a greater volumes is needed ?
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my bad.....50 it is
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Is the products side correct ? Dichlorobutane...
-
2 H molecules from the alkane cannot be substituted in one go.
You only change the position of the Cl, not the number. This process happens in stages.
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2 H molecules from the alkane cannot be substituted in one go.
You only change the position of the Cl, not the number. This process happens in stages.
The MS says dichlorobutane or 2-chlorobutane (i chose this one as my final answer)..
So how is dichlorobutane written ?
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2-chlorobutane is possible....dichlorobutane happens in the second step
What you have drawn is dichlorobutane
2-chlorobutane is Cl on the 2nd carbon
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When drawing a magnification of something in Bio, Does everything have to be in the right proportion? Meaning if you've magnified the legs of an insect by 2, then the body and head and eyes should also have to be magnified by 2. Does everything have to be exact?
How does magnification work???
-
yes everything is magnified by the same amount...so all the parts should approximately be magnified equally
magnification= observed size/ actual size
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I suck at drawing so what's the easiest way to do this??? I'm doing May-June 2003 Paper 6 Question 3.
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for this one they won't really sit to check ur magnification....but u must enlarge wisely....don't deform the shape of the slug
and simply label the muscular foot, tentacles and the mantle http://commons.wikimedia.org/wiki/File:Slug_parts.png
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Damn!!! It's like u no evrything.
Thanks very much!!! And if I have more doubts I know now who I have to ask. HeHeHeHeHeHeHeHeHeHeHeHeHeHeHeHeHeHe!!!!!!!!
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oh :-[ :-[ thank you
yaa sure...i'll do my best to help you
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U can always send me a few, if you get ur hands too full, nid, I just cant help as proactively as before, cuz i have a lot of stuff to do.
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That was very kind of you dude...thank you :)
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You Welcome!!! :) Do you know what a suck-back problem is??? It was one of the answers on the chem papers that i was doing for paper 6.
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I can answer with relevance to the question...so put the paper up...let me see the setup...then i'll come to know of it
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Here it is. Question 6c. And also 6a.
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heat applied more towards the end of the test tube...close to the liquid alkane...
okay, if the heat is turned off first, there is a sudden drop in pressure, the water could be drawn into the tube...this is suck-back
To prevent this, the delivery tube is taken off first
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Hey nid, do u have some REALLY good Chem and Bio Paper 6 Notes. I'm just looking for paper 6 only... I would appreciate the help...
-
i will look for it
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I have requested the Dude to upload paper 6 notes, this is what i had. For chem.
-
any notes for
- outline the use of microorganisms and fermenters to manufacture the antibiotic
penicillin
- describe the role of the fungus Penicillium in the production of antibiotic penicillin
and
- discuss the adaptations of the leaf, stem and root to three contrasting environments, to include pond, garden and desert, with emphasis on local examples (where appropriate) and the factors described in the core.
-
hey can somebody tell n explain appropriately the ans to this ques.. :)
-
any notes for
- outline the use of microorganisms and fermenters to manufacture the antibiotic
penicillin
- describe the role of the fungus Penicillium in the production of antibiotic penicillin
and
- discuss the adaptations of the leaf, stem and root to three contrasting environments, to include pond, garden and desert, with emphasis on local examples (where appropriate) and the factors described in the core.
hmm.....is this co-ordinated science? If you want specific notes, i would have to see the syllabus
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hey can somebody tell n explain appropriately the ans to this ques.. :)
Flour dust suspended in air is explosive -- as is any mixture of a finely powdered flammable substance with air...
more fine the particles are, more the risk of an explosion
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hey can somebody tell n explain appropriately the ans to this ques.. :)
In short... the greater the surface area the greater the speed of the reaction, hence more chance of a BIG BOOM !
I know nid explained it already but I wanted to give my 2 cents. :)
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thanks :)
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hmm.....is this co-ordinated science? If you want specific notes, i would have to see the syllabus
no i copied these from bio syllabus 0610
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also if any1 has the diagram of human insulin genetic engineering (simple igz required 1) plz post it here
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if you want for human insulin and genetic engineering( i mean both differently) then here they are..
i mean maybe for insulin you xcan go to this website it has picture as well as something ore if you like it:
http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/pancreas/insulin_struct.html
for genetic engineering i have attached..
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@Angel of Love n nid404 congratulations!! :D
@nid404 thanku so much! i already figured that out in igcse complete chemistry pg 151..:P
jus logged on 2 see wat replies i'd get :P :D
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hi,
can somebody explain to me why antibiotics kills bacteria but not viruses??
it's in the syllabus....
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hi,
can somebody explain to me why antibiotics kills bacteria but not viruses??
it's in the syllabus....
What antibiotics do is they prevent formation of bacterial cell wall, thus leading to their death
Antibiotics target only bacterial function and structure and so have no effect on virus'
By Nid
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What antibiotics do is they prevent formation of bacterial cell wall, thus leading to their death
Antibiotics target only bacterial function and structure and so have no effect on virus'
By Nid
Whoah, you dont need to know that much, simple that they dont work on viruses, because virusesbacteria do not show the characteristics of viruses. You will not be asked this question though, in the CIE spec.
You will be given questions like why has penicillin becomes less effective??
Because strains of Bacteria become more resistant to it.
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um how do i revise for paper 6 and 1 chem IGCSE on the night/day before the Eaxm itself?
and
um how do i revise for paper 1 biology IGCSE on the night/day before the Eaxm itself?
thx in advance
-
um how do i revise for paper 6 and 1 chem IGCSE on the night/day before the Eaxm itself?
and
um how do i revise for paper 1 biology IGCSE on the night/day before the Eaxm itself?
thx in advance
Past-papers...Past-papers
Of course if you have time, revise your notes first, then just keep on doing past-papers,even if you have done them before.
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thx A.F.
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Whoah, you dont need to know that much, simple that they dont work on viruses, because virusesbacteria do not show the characteristics of viruses. You will not be asked this question though, in the CIE spec.
You will be given questions like why has penicillin becomes less effective??
Because strains of Bacteria become more resistant to it.
thx to both of you....
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any notes for
- outline the use of microorganisms and fermenters to manufacture the antibiotic
penicillin
- describe the role of the fungus Penicillium in the production of antibiotic penicillin
and
- discuss the adaptations of the leaf, stem and root to three contrasting environments, to include pond, garden and desert, with emphasis on local examples (where appropriate) and the factors described in the core.
The fermenters are used to manufacture antibiotics to provide a sterile environment and optimum conditions ie optimum temperature and pH. Microorganisms speed up the process of producing antibiotics.
Adaptations of plants:
POND: eg: canadian pondweed
- stomata present on upper surface only to absorb carbon dioxide and give out oxygen easily and transpiration is not a problem as water is in abundance.
- The upper epidermis contains chlorophyll as absorbing light energy through the water is difficult therefore it increases photosynthesis
- leaves are thing and ribbon-like in order not to get ruptured by water currents
- the stem contains air spaces to provide buoyancy and to allow diffusion of gases throughout the plant. This provide energy to absorb nutrients by active uptake as they respire aerobically
- stems are flexible and ribbon-like
- roots are virtually absent as water is in abundance hence they do not need to absorb water from the soil.
DESERT: eg: cactus
- leaves are reduced to spines to protect the plant from being eaten and to reduce water loss and in order not to get ruptured by strong desert winds
- stem contains chlorophyll to carry out photosynthesis, it is covered in cutilce to prevent water loss
- stem stores water and nutrients
- stem is short and juicy in order not to get ruptured by strong desert winds
- roots are long to provide anchorage and to reach the water table deep underground
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can someone please give me the answer to the following questions:
1. describe the passage of water from blood in the aorta to its excretion via the urethra
2. outline a treatment of sewage which would produce re-usable water
3.suggest how the build up of sticky mucus would affect a sufferer of cystic fibrosis
4. suggest how a high salt intake can be dangerous to a person's health
thankyou in advance!
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can someone please give me the answer to the following questions:
1. describe the passage of water from blood in the aorta to its excretion via the urethra
2. outline a treatment of sewage which would produce re-usable water
3.suggest how the build up of sticky mucus would affect a sufferer of cystic fibrosis
4. suggest how a high salt intake can be dangerous to a person's health
thankyou in advance!
5 hrs
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The fermenters are used to manufacture antibiotics to provide a sterile environment and optimum conditions ie optimum temperature and pH. Microorganisms speed up the process of producing antibiotics.
Adaptations of plants:
POND: eg: canadian pondweed
- stomata present on upper surface only to absorb carbon dioxide and give out oxygen easily and transpiration is not a problem as water is in abundance.
- The upper epidermis contains chlorophyll as absorbing light energy through the water is difficult therefore it increases photosynthesis
- leaves are thing and ribbon-like in order not to get ruptured by water currents
- the stem contains air spaces to provide buoyancy and to allow diffusion of gases throughout the plant. This provide energy to absorb nutrients by active uptake as they respire aerobically
- stems are flexible and ribbon-like
- roots are virtually absent as water is in abundance hence they do not need to absorb water from the soil.
DESERT: eg: cactus
- leaves are reduced to spines to protect the plant from being eaten and to reduce water loss and in order not to get ruptured by strong desert winds
- stem contains chlorophyll to carry out photosynthesis, it is covered in cutilce to prevent water loss
- stem stores water and nutrients
- stem is short and juicy in order not to get ruptured by strong desert winds
- roots are long to provide anchorage and to reach the water table deep underground
thx :D
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WHere in the car is a catalytic converter fitted in a vehicle?
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WHere in the car is a catalytic converter fitted in a vehicle?
The Catalytic Converter is a device fitted in the exhaust system of your car that effectively reduces the harmful exhaust gases entering the atmosphere.
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can someone please give me the answer to the following questions:
1. describe the passage of water from blood in the aorta to its excretion via the urethra
Blood is got to the kidney via renal artery. The renal artery divides into a great number of arterioles and capillaries, mostly in the cortex. Each arteriole leads to a glomerulus. The pressure in the glomerulus causes part of the blood plasma to leak the capillary walls. The RBC's and proteins in plasma r too big to pass out. The fluid that moves out contains mainly water with dissolved salts, urea, glucose and uric acid. The process by which the fluid is filtered out of the blood by the glomerulus is called ultrafiltration. The filtrate from the glomeruls collects in the renal capsule and trickles down the renal tubule. As it does so, the capillaries which surround it absorb the substance the body needs. All the glucose is absorbed, with much of the water(depends on the state of hydration). The some salts r taken back to keep the correct con in the blood. This process of taking back the required substances is called selective reabsorption.
Substances that r not needed pass further down to the collecting duct into the pelvis of the kidney. From here the fluid, now called urine, passes down the ureter to the bladder.
Nephron- A single glomerulus with its renal artery, renal tubule and blood capillaries
visit the site for a good animation http://www.biologymad.com/resources/kidney.swf
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can someone please give me the answer to the following questions:
2. outline a treatment of sewage which would produce re-usable water
http://www.ehow.com/about_5368260_sewage-water-treatments.html
I dunno how much of it you wanted....i you told me the marks, i would've written down a good answer
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can someone please give me the answer to the following questions:
3.suggest how the build up of sticky mucus would affect a sufferer of cystic fibrosis
Cystic fibrosis is an inherited disease which affects the lungs and digestive system. It results from mutation in a gene responsible for making a protein which is involved in the transport of ions across cell boundaries.
The effect is to produce a sticky mucus which clogs the lungs and can lead to serious infection. A similar sticky mucus also blocks the pancreas (a part of the digestive system) which provides enzymes for breaking down food. This gets in the way of the processes which convert the food into molecules which can be absorbed by the body.
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Hi, can you please help me solve the following question
0.5 g of magnesium is added to a solution containing 3.0 g of ethanoic acid. Which is the limiting reagent and how many moles of the other reagent are left unreacted?
Mg + 2CH3COOH ---> (CH3COO)2Mg + H2
Please explain fully with all the steps.
And can you please give an excellent website on moles?
Thanks in advance!
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first find the number of moles of each reactant
no. of moles = mass/molecular mass
so mg=0.5g and ch3cooh=3g
and ram of mg=24 and rmm of ch3cooh=60
moles of mg=0.5/24 moles of ch3cooh=3/60
=0.02 =0.05
now use mol ratio to find the number of moles used
(take the lower value from your answer of the no. of moles)
mg : ch3cooh
1 : 2
0.02 : x
x=2*0.02
x=0.04 moles
so ultimately your limiting reagent will be mg cause it was all used up in the reaction
and out of the 0.05 moles of ch3cooh, 0.04 were used up
hope i was able to help
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Thanks haris, now i understand the calculations part, however I dont quite understand why mg is the limiting reagent and how can we know if it has been used up? Other than this, you didnt answer how many moles of the other reagent (in this case ethanoic acid) are left unreacted.
By the way, do u knw any good websites on moles?
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hey ;D
Can anyone or NID help me wit a question on may une 2009 chemistry- question 5b
Please help my exams are nxt week!
Thank you.
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As soon as i'm back from school :)
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hey how are we supposed to stdy for organic chemistry especially the structures for starch/carbs or Nylon n Terylene..(chemical reactions involved too)
so are v supposed to kno them by heart?? or jus no the idea..
hav these structures been asked in any past paper because i might hav missed them.
thnkx
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Yes the structures are asked hell lotta times in paper3. U have to study them "by heart".
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okay thanks so they are basically asked in paper 3 right??
i hav a mini vacation before chemistry paper3 (10 days off!!) so tht might give me time to learn them properly
im strong with the rest of organic tho..
thanks..
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Cystic fibrosis is an inherited disease which affects the lungs and digestive system. It results from mutation in a gene responsible for making a protein which is involved in the transport of ions across cell boundaries.
The effect is to produce a sticky mucus which clogs the lungs and can lead to serious infection. A similar sticky mucus also blocks the pancreas (a part of the digestive system) which provides enzymes for breaking down food. This gets in the way of the processes which convert the food into molecules which can be absorbed by the body.
thank you soo much Nid! That really helped! =)
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okay thanks so they are basically asked in paper 3 right??
i hav a mini vacation before chemistry paper3 (10 days off!!) so tht might give me time to learn them properly
im strong with the rest of organic tho..
thanks..
Ur welcome.
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Thanks haris, now i understand the calculations part, however I dont quite understand why mg is the limiting reagent and how can we know if it has been used up? Other than this, you didnt answer how many moles of the other reagent (in this case ethanoic acid) are left unreacted.
By the way, do u knw any good websites on moles?
limiting reagent is the reactant which will be used up first (fewer number of moles), therefore causing the reaction to stop
in this case there r fewer moles of mg than ch3cooh. so mg will get used up and then since there is no more mg, reaction is stopped
as to the moles of ch3cooh, i hv written that out of 0.5 moles, 0.4 will be used. so the unreacted ch3cooh is 0.1 moles.
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limiting reagent is the reactant which will be used up first (fewer number of moles), therefore causing the reaction to stop
in this case there r fewer moles of mg than ch3cooh. so mg will get used up and then since there is no more mg, reaction is stopped
as to the moles of ch3cooh, i hv written that out of 0.5 moles, 0.4 will be used. so the unreacted ch3cooh is 0.1 moles.
THANKS ALOT!! I totally understand it now!
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anytime :)
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hey ;D
Can anyone or NID help me wit a question on may une 2009 chemistry- question 5b
Please help my exams are nxt week!
Thank you.
post the paper up plz :)
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Hey nid, can you please help me with question number 5c. The answer says it is a catalyst but I need an explanation.
I also need help on question number 6.
Thanks!!!
By the way, did u find some bio paper 6 notes???
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Hey nid, can you please help me with question number 5c. The answer says it is a catalyst but I need an explanation.
I also need help on question number 6.
Thanks!!!
By the way, did u find some bio paper 6 notes???
In the paper you attached what question do you need help in ?
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My bad 5g and 6. Srry!!!
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5g) Manganese Oxide/Catalysr, reasons : Black solid(Transition Metals have color), Effervescence because of Oxygen released as it speeds up the breaking with H2O2, glowing splint relit because of oxygen again.
Q6) This is a very common question, learn the steps to extract a color from a solution.
Add water, crush the berries, finally, decant it to remove the insoluble waste. U can also warm it.
b) use the indicator in an acid, base and a neutral solution , if its an effective indicator it shud give out three different colors.
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does anybody know who got A* in chemistry??
i've never heard anybody got an A* in chem....
is it ossible to get an A* or is it very hard??
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Many have gotten A stars. You are an assured an A* if u get 90 or above...
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There are many who get A* in Chemistry, i got an A* too. Yes, above 90%ile, i got 95%ile.
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There are many who get A* in Chemistry, i got an A* too. Yes, above 90%ile, i got 95%ile.
woww man!! so now i can ask u questions....
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U can ask anyone, specially Nid. ~A.F~ and The Mysterious Dude are great too.
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Bring 'em on.
I got 95 too...
but i take time to answer cuz im preparing myself for physics(my not so good subject) ::)
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can somebody describe to me what is fermentation in one sentence??
thx
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Fermentation is the breakdown of organic material with effervescence and release of heat.
For years, ethanol has been made by fermentation of glucose.
Glucose --> Ethanol + Carbondioxide
(Yeast, Absence of Air)
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the conversion of a carbohydrate such as sugar into an acid or an alcohol (from teacher's notes)
the anaerobic conversion of sugar to carbon dioxide and alcohol by yeast (from a book)
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thanks!!
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there is smthn i really need and i've been tryin my best to find it but i still didn't find it ........ i did chem ig paper 1 june & November 1999 as well as 2000 and i need the answers for these papers :-\
can someone plz give me a link of the m.s. of these two papers ? :'(
thx alot :-[
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I'm not sure if these are available.
Post your questions here, I'll answer as soon as I can :)
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there is smthn i really need and i've been tryin my best to find it but i still didn't find it ........ i did chem ig paper 1 june & November 1999 as well as 2000 and i need the answers for these papers :-\
can someone plz give me a link of the m.s. of these two papers ? :'(
thx alot :-[
here
http://www.freeexampapers.com/Dndex.php?d=SUdDU0UvQ2hlbWlzdHJ5L0NJRS8xOTkzLTIwMDM=
this file contains ms for p1, p3, and p6 from 1993-2000
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can someone plz explain to me the nitrogen cycle
Thanks
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http://www.nicksnowden.net/Module_3_pages/nitrogen_cycle.htm
go through this.
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here
http://www.freeexampapers.com/Dndex.php?d=SUdDU0UvQ2hlbWlzdHJ5L0NJRS8xOTkzLTIwMDM=
this file contains ms for p1, p3, and p6 from 1993-2000
i checked it and i only found the ms for paper 2,3 & 6 ...it doesn't have paper 1 ............. do u have another link
thx in advance
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there is smthn i really need and i've been tryin my best to find it but i still didn't find it ........ i did chem ig paper 1 june & November 1999 as well as 2000 and i need the answers for these papers :-\
can someone plz give me a link of the m.s. of these two papers ? :'(
thx alot :-[
people plz do help me !! ??? :-\ :'(
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put the paper up, we'll solve it for you.
To find old papers off the net is very difficult
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okay .... just a few seconds .... plz solve both june and nov for 1999 & 2000 ..... cuz i need it before tomorrow ...thx
i'll upload it ....wait a sec
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then post them ::) :P
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then post them ::) :P
from page 157 till i guess 215
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/1993-2003/ChemistryExamP1.pdf
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lol golden girl, that wasn't for you...that was for Ari...he says he has the MS... :D
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lol golden girl, that wasn't for you...that was for Ari...he says he has the MS... :D
Sorry, I thought you meant for 2009.
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Ohk....I'll solve these when i get time
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i checked it and i only found the ms for paper 2,3 & 6 ...it doesn't have paper 1 ............. do u have another link
thx in advance
it has ms for p1
right at the end of the file
check again
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Can anyone explain the CHEMICAL CELL!! daamn, i hate it -.-
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Fuel cell
These are Voltaic cells in which the reactants are continuously supplied to the electrodes. These are designed to convert the energy from the combustion of fuels such as H2, CO, CH4, etc. directly into electrical energy. The common example is hydrogen-oxygen fuel cell as described below,
In this cell, hydrogen and oxygen are bubbled through a porous carbon electrode into concentrated aqueous sodium hydroxide or potassium hydroxide. Hydrogen (the fuel) is fed into the anode compartment where it is oxidised. The oxygen is fed into cathode compartment where it is reduced. The diffusion rates of the gases into the cell are carefully regulated to get maximum efficiency. The net reaction is the same as burning of hydrogen and oxygen to form water. The reactions are
At anode : 2 [ H2(g) + 2OH-] (aq) --->2H2O (I) + 2e-
At cathode : O2 (g) + 2H2O(I) + 4e- ---> 4OH- (aq)
Overall reaction : 2H2 (g) + O2 (g) ---> 2H2O (I)
Each electrode is made of porous compressed carbon containing a small amount of catalyst ( Pt, Ag or CoO ). This cell runs continuously as long as the reactants are fed.
(http://www.transtutors.com/userfiles/image/Navjeevan/electrode-potential1.JPG)
Advantages
(1) High efficiency : The fuel cells convert the energy of a fuel directly into electricity and therefore, they are more efficient than the conventional methods of generating electricity on a large scale by burning hydrogen, carbon fuels. Though we expect 100 % efficiency in fuel cells, so far 60 – 70% efficiency has been attained. The conventional methods of production of electrical energy involve combustion of a fuel to liberate heat which is then used to produce electricity. The efficiency of these methods is only about 40%.
(2) Continuous source of energy : There is no electrode material to be replaced as in ordinary battery. The fuel can be fed continuously to produce power. For this reason, H2 - O2 fuel cells have been used in space crafts.
(3) Pollution free working : There are no objectionable byproducts and, therefore, they do not cause pollution problems. Since fuel cells are efficient and free from pollution, attempts are being made to get better commercially
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it has ms for p1
right at the end of the file
check again
ohh ya :-[ thx By the way :)
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no probs 8)
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guys whenever a question comes and any oxide "batani7!!" ....i don't anythin hat's related to oxides ..... and stuff ...the only thing i kno abt oxides is that the non-mtealic r acidic and the metallic r basic ..and there r some amphotaric ....... can someone plz explain to me ..
ummm ohh and another thing ....there is this weird question that i'd like u to look at, it's jun 2000 paper 1 chem ig question 26) ..
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/1993-2003/ChemistryExamP1.pdf
thx in advance
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when the questions says smthn is below ph 7 , does that mean it's acidic or basic?
thx in advacne :D
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below pH 7 - acidic. u must be clear with these basic concepts by now, acids and bases is a very common topic. :)
By the way, @hesham - heres the working wid acid electrolyte.
the hydrogen (H2) loses electrons.. 2H2 --> 4H+ + 4e- which travel through the circuit to the cathode and react with O2..also the H+ ions from the acid electrolyte meets the electrons and O2 at the cathode
the reaction
O2 + 4H+ + 4e- = 2H2O
---
The H+ ions removed from the electrolyte are replaced by those produced at the anode.
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thanks adi +rep
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guys whenever a question comes and any oxide "batani7!!" ....i don't anythin hat's related to oxides ..... and stuff ...the only thing i kno abt oxides is that the non-mtealic r acidic and the metallic r basic ..and there r some amphotaric ....... can someone plz explain to me ..
ummm ohh and another thing ....there is this weird question that i'd like u to look at, it's jun 2000 paper 1 chem ig question 26) ..
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/1993-2003/ChemistryExamP1.pdf
thx in advance
Okay the answer is 26 B. Heres the explanation coming up....
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guys whenever a question comes and any oxide "batani7!!" ....i don't anythin hat's related to oxides ..... and stuff ...the only thing i kno abt oxides is that the non-mtealic r acidic and the metallic r basic ..and there r some amphotaric ....... can someone plz explain to me ..
ummm ohh and another thing ....there is this weird question that i'd like u to look at, it's jun 2000 paper 1 chem ig question 26) ..
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/1993-2003/ChemistryExamP1.pdf
thx in advance
cud u be more specific abt oxides, i mean what exactly do u want to know abt?
and wat the helll is batani7? never heard abt that :-/
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Okay the answer is 26 B. Heres the explanation coming up....
Magnesium and Zinc react with steam to form HYDROGEN !!! SO those two arent correct.
Copper is unreactive and doesnt react with steam so it can be the correct one.
Thus, Iron is the only one that when heated and reacted with Steam forms its OXIDE and HYDROGEN GAS.
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@Ari - its B, not A.
Copper will not displace Hydrogen. Iron will. and give release the hydrogen.
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@Ari - its B, not A.
Copper will not displace Hydrogen. Iron will. and give release the hydrogen.
Sorry, it was a typo I meant B. I changed it and gave an explanation. :D
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its okay. +rep
anyway, gas Q is H2, as the metal will displace hydrogen not oxygen.
out of copper and iron, iron is above hydrogen in the series, thus iron.
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cud u be more specific abt oxides, i mean what exactly do u want to know abt?
and wat the helll is batani7? never heard abt that :-/
i'm srry abt batani7 , it's actually an arabian MSN word ...srry i though u were arabian :(....my bad :-[
as for the oxides ....i guess i just wanna to know where is hydrogen in the reactivity series........ actually the whole reactivity series ..i want it all .... can u give me a link that shows the reactivity series ...includin carbon and hydrogen ....cuz the one i have doesn't have hydrogen ....no idea y?!?!
as for the oxides .....i don't kno who reacts with what to give for ex hydrogen ,u see
hope u got my point ...
thx ain advance
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(http://www.frankswebspace.org.uk/ScienceAndMaths/chemistry/reactivitySeries_Files/reactivitySeries.gif)
Here. Right click and select view image to enlarge
Only a metal compound higher than Hydrogen can displace it from steam and hence form METAL OXIDE and STEAM
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(http://www.frankswebspace.org.uk/ScienceAndMaths/chemistry/reactivitySeries_Files/reactivitySeries.gif)
Here. Right click and select view image to enlarge
Only a metal compound higher than Hydrogen can displace it from steam and hence form METAL OXIDE and STEAM
thx
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the link, here : http://www.zephyrus.co.uk/thereactivityseries.html
and abt the reactions, im still not sure wat u want.
"who reacts to what" completely depends on the q. like here.
steam reacted with a metal i.e iron
Steam - H2O
iron - Fe
H2O + Fe --> FeO + H2.
Iron displaced Hydrogen.
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the link, here : http://www.zephyrus.co.uk/thereactivityseries.html
and abt the reactions, im still not sure wat u want.
"who reacts to what" completely depends on the q. like here.
steam reacted with a metal i.e iron
Steam - H2O
iron - Fe
H2O + Fe --> FeO + H2.
Iron displaced Hydrogen.
okay i'll give u all the questions that i have doubt in that r related to oxides ,k ? ....but plz do explain cuz i kno what the answers r cuz of the ms ..,k?
well herei go :
jun2001 question 14)
nov 2001 question 21)
nov 2003 q 16) ..19) and 26)
jun 2004 q 9)..14)..26)
nov q 11)
i kno that's alot .....well my bro is pain in the neck .hence i'll sign out right now ...but i'll be back abd 2 hours later or smthn ..... and i really would apprectiate it if u would have answered me by then ...
thx alot !!!
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okay i'll give u all the questions that i have doubt in that r related to oxides ,k ? ....but plz do explain cuz i kno what the answers r cuz of the ms ..,k?
well herei go :
jun2001 question 14)
nov 2001 question 21)
nov 2003 q 16) ..19) and 26)
jun 2004 q 9)..14)..26)
nov q 11)
i kno that's alot .....well my bro is pain in the neck .hence i'll sign out right now ...but i'll be back abd 2 hours later or smthn ..... and i really would apprectiate it if u would have answered me by then ...
thx alot !!!
june 04
9) A ..has to be only one showing a correct formula for lead(II)Nitrate!! Pb(NO3)2
14) D ..hydrogen in a fuel always combines with air
26) A .. z least reactive as it occurs naturally as the metal
nov 04
11) A ..copper oxidizes when heated in air
will take time to ans others havta hav my dinner!..:)
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june 2001 q14 - C. the gas released is obviously hydrogen because the metal will displace hydrogen from steam. steam is reduced because the H has gained an electron.
nov 2001 - 21 - A. Calcium oxide + HCl --> Calcium chloride + water. litmus red (acid) to blue (excess CaO)
nov 2003 - 16) B, lead oxide is reduced, lead remains, H20 (steam) dries up and adds to the drying agent.
19) C, neutralization because of acid + base. filtration at last.
26) B, hydrogen will displace copper.
june 04 - 9 - A, perfectly balanced
14) D - combustion
26) A. electrolyzing is used for very reactive metals. unreactive metals occur naturally
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nov 03
16) B .. lead oxide is decomposed hence mass decreases and O2 is displaced on the right so ova there mass inc.
19) C .. MgSO4 is a salt formed by reacting a base and an acid, they neutralize to form a salt thn the solution has to be filtered to seperate
26) B .. only copper can be displaced by Hydrogen..study reactivity series..
i feel these are too easy..im happy.. evn i had a lot of probs solvin such ques ..:)
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thx alot , both of u !! ....... i feel like i awe u alot .....really thx alot !!
~VIN1094~ - i just want to know how did u get to feel they're too easy ..in other words , what did u do to feel so not worried/so comfortable with chemistry paper 1 or even such questions?...
thx in advance
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thx alot , both of u !! ....... i feel like i awe u alot .....really thx alot !!
~VIN1094~ - i just wanna kno how did u get ot feel there too easy ..in other words , what did u do to feel so not worried/so comfortable with chemistrey paper1 or even such question?...
thx in advance
ur welcome
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thx alot , both of u !! ....... i feel like i awe u alot .....really thx alot !!
~VIN1094~ - i just wanna kno how did u get ot feel there too easy ..in other words , what did u do to feel so not worried/so comfortable with chemistrey paper1 or even such question?...
thx in advance
ur welcome
its all practice which made me confidant .. if i had to say jus kno ur concepts well .. the thing is chemistry paper 1 wasn't too easy until a month ago but as u might kno im preparing fo boards now n obvi i might hav studied chemistry ..
but i lack miserably in stoichiometry .. i cant even spell it properly !! :p
i'd recommend u study from "complete igcse by RoseMarie Gallaghar and Paul Ingram" .. an amazing book gets all your doubts cleared !! :)
if u dont hav it u might consider visiting ur school library .. its still not late :)
in fact complete is good for all 3 sciences ..
gud luck !! :) (guess wat this is my 100th lucky post .. :P)
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can somebody tell me what's the difference between ester link and amide link???
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can somebody tell me what's the difference between ester link and amide link???
Esters are basically umm.. when u react alcohols with carboxylic acids u get esters ..
say ..
propanoic acid + butanol <===> butylepropanoate
they are reversible .. (pls. dont go over my spellings, another thing im concerned about my exams)
amide link is where a couple of monomers have joined .. im sorry i dont have any means to show you in a graphical way .. :(
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amide link or peptide link is formed when the amine group of one monomer reacts with the carboxylic acid of another in a condensation polymerisation reaction...
O
||
NH2 -(R1) -C-N- (R2)-COOH
|
H
the CONH bond is the amide link. R1 and R2 represent different monomer units(amino acids). By product of this reaction is water
-
hmm Thanks .. :)
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amide link or peptide link is formed when the amine group of one monomer reacts with the carboxylic acid of another in a condensation polymerisation reaction...
O
||
NH2 -(R1) -C-N- (R2)-COOH
|
H
the CONH bond is the amide link. R1 and R2 represent different monomer units(amino acids). By product of this reaction is water
thanks...can u tell me what is ester link?ur explanation is easy to understand ;D
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C-C=O O
| + OH-C-C = ||
C-C - O - C-C
OH
(Ethanoic Acid) (Ethanol) (Ethyle Ehanoate )
The ester Link is the:
( O )
( || )
( C - 0 )
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check this image for ester : http://meta.filesmelt.com/downloader.php?file=ester.bmp
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check this image for ester : http://meta.filesmelt.com/downloader.php?file=ester.bmp
this should be enough :)
thanks
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thanks guys for everything!! :D
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Heyy guys,
Hope your preparations are rocking.
Nyways I have few doubts in bio.
Q1) Describe the use of fermenter in the production of :- (i) Antibiotics [3 marks] ; (ii) Single - Cell Protein [3 marks]
Q2) Explain the advantages & the dangers of using antibiotics to treat infections. [ 5 marks]
Q3) Describe the use of antibiotics for the treatment of diseases. [ 3 marks]
Thanks guys...
All the BEST!!! (Y)
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1) It is basically the same... The only difference is that in this fermenter u use a bacteria like pencillium for making pincillin and the other uses single cell protein to make protein.
The process:
First The bacteria is put with sugar and other types of food that it feeds on. Air is also let in the fermenter. This allows the bacteria to grow normally. When they are mature they start secreting the product wanted (pencillin or protein). When the process is over the culture (the mixture) is filtered and treated to obtain the pincillin or protein.
Also u need to know that the mixture is filtered throughout the process. This is very important for: 1- Keeps the fungus in contact with the fresh supplies of nutrients. 2- mixes oxygen throughout the fermenter. 3- but also 'rolls the fungus up into little pellets'. This makes it quite easy to seperate the liquid part of the culture.
2)I dont have enough info, but what i know is... Adv: kills infections (duh). this: can cause the disease to becomes resistant to this particular antibiotic if taken for a long time or u stopped taking it b4 the end of the period ur doctor prescribed. This is why medicine companies need to make new medicines each year
3) m pretty sure u dont need to know about this in details in IGCSE. It has smth to do with making ur body antibodies active and so go fight this mf disease :P But i dont think we need to know this...
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hey <3 ur signature .. :P
-
Hey, sry but i'll ask something silly, if in a question they asked us 2 draw a SUITABLE GRAPH, is it ok if we drew a bar chart?
-
depends on what kinda question it is.
Give me examples....I'll tell you how to distinguish then :)
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Depends on the information given .. if its comparing two or three quantities u may draw one without worrying .. :)
-
depends on what kinda question it is.
Give me examples....I'll tell you how to distinguish then :)
oh sorry i ignored the warning message :(
-
Biology Paper 6, O/N 2007 question 1
-
you haven't sinned :P
It's k ;)
-
Biology Paper 6, O/N 2007 question 1
yes you can draw a bar chart
-
the pH on the x-axis and the time on the y-axis right? By the way its nt a comparision
-
yes
-
you can also try drawing a line graph..
-
guys can someone plz explain to me question 15) in novemeber 2002 chem paper 1 , plz i really need it :'(
i wanna know what liberated means and y the answer is A?
thx in advance
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guys can someone plz explain to me question 15) in novemeber 2002 chem paper 1 , plz i really need it :'(
i wanna know what liberated means and y the answer is A?
thx in advance
15 - D, the ignition released heat, which increased the rate of burning as methane is flammable.
-
can u plz tell me what compounds/things that r insoluble +++ and what r the things that are flammable?
thx in advance
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Insoluble compounds.
Chlorides, bromides, iodides of silver and lead.
Sulfates of Calcium, barium and lead.
All hydroxides except those of group 1
All carbonates except those of group 1
Metal oxides except group 1 and 2s.
--
Flammable : Most alkanes, kersoene, petrol and naturally occurring oils.
-
Thanks a lot adi
-
NO PROBLEM.
-
Hello all, i'm newbie here...
I take A-Level for Biology on this May-June session and still need some helps.
May i ask my doubt about how to answer the question, whether the answers are short and simple like in the mark scheme or we must explain more on every point in mark scheme ? And what is the meaning of word "reference" in mark scheme?
Bonus Question: How to answer the last part (looong essay part) of P4 ?
Need your help, because my school teacher never give us explanation about it.
Thx before and sorry if my questions are out of the thread :)
-
Hello all, i'm newbie here...
I take A-Level for Biology on this May-June session and still need some helps.
May i ask my doubt about how to answer the question, whether the answers are short and simple like in the mark scheme or we must explain more on every point in mark scheme ? And what is the meaning of word "reference" in mark scheme?
Bonus Question: How to answer the last part (looong essay part) of P4 ?
Need your help, because my school teacher never give us explanation about it.
Thx before and sorry if my questions are out of the thread :)
this is the igcse forum
i think you should go here-https://studentforums.biz/index.php/board,82.0.html
-
this is the igcse forum
i think you should go here-https://studentforums.biz/index.php/board,82.0.html
Thanks +rep.
-
Insoluble compounds.
Chlorides, bromides, iodides of silver and lead.
Sulfates of Calcium, barium and lead.
All hydroxides except those of group 1
All carbonates except those of group 1
Metal oxides except group 1 and 2s.
--
Flammable : Most alkanes, kersoene, petrol and naturally occurring oils.
thx :D
-
Insoluble compounds.
Chlorides, bromides, iodides of silver and lead.
Sulfates of Calcium, barium and lead.
All hydroxides except those of group 1
All carbonates except those of group 1
Metal oxides except group 1 and 2s.
--
Flammable : Most alkanes, kersoene, petrol and naturally occurring oils.
OMG I freakin h8 this and the Cations/Anions Test man >:( Can't manage to memorize them :( :P
-
I need help with moles!
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2005%20Jun/0620_s05_qp_3.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2005%20Jun/0620_s05_qp_3.pdf)
Q4d! I got the moles for CaSO4 and H20 (0.58 mol and 1.16 mol, respectively) but I'm confused with the x. Do you add the moles for CaSO4 and H20 to get x ???
Secondly, http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2003%20Nov/0620_w03_qp_3.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2003%20Nov/0620_w03_qp_3.pdf)
Q5d! (moles again) My question is how do you know that that 0.125 mol of SO2Cl2 was formed? :-\
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Q4d! I got the moles for CaSO4 and H20 (0.58 mol and 1.16 mol, respectively) but I'm confused with the x. Do you add the moles for CaSO4 and H20 to get x
Do it step by step - dont jump.
First find the no. of moles of CaSO4
79.1/136 = 0.582 moles
20.9/18 = 1.16 moles
Notice we are in effect finding the empirical formula hence:
0.582/0.582 = 1 and 1.16/0.582 = 2
Thus X = 2
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Can this page ALSO help me with Bio??
If it can
Can someone please help me:
My school gave us waaaaaaaaaaay too much information..
And I just want to be sure:
When making cheese,bread, wine,yoghurt, and beer, what do we have to know EXACTLY
Our school gave us steps and all those stuff
Should we ONLY know what the study guide tells us on this part (the results, and a brief explanation)???
-
Do it step by step - dont jump.
First find the no. of moles of CaSO4
79.1/136 = 0.582 moles
20.9/18 = 1.16 moles
Notice we are in effect finding the empirical formula hence:
0.582/0.582 = 1 and 1.16/0.582 = 2
Thus X = 2
Oh, I get it now thanks Ari! :)
-
Can this page ALSO help me with Bio??
If it can
Can someone please help me:
My school gave us waaaaaaaaaaay too much information..
And I just want to be sure:
When making cheese,bread, wine,yoghurt, and beer, what do we have to know EXACTLY
Our school gave us steps and all those stuff
Should we ONLY know what the study guide tells us on this part (the results, and a brief explanation)???
I'll ask nid to help you.
Oh, I get it now thanks Ari! :)
No problemo ;)
-
OMG I freakin h8 this and the Cations/Anions Test man >:( Can't manage to memorize them :( :P
chill ..... u must understand it first so that when u memorize it'll be easy for u to memorize ,k ?
-
Can this page ALSO help me with Bio??
If it can
Can someone please help me:
My school gave us waaaaaaaaaaay too much information..
And I just want to be sure:
When making cheese,bread, wine,yoghurt, and beer, what do we have to know EXACTLY
Our school gave us steps and all those stuff
Should we ONLY know what the study guide tells us on this part (the results, and a brief explanation)???
You need to know the steps ofc.
We have yoghurt making, baking, brewing
Yeast can respire without oxygen, fermenting sugars to produce carbon dioxide and alcohol.
In baking:
-a mixture of yeast and sugar is mixed with bread dough;
-the mixture is left in a warm place;
-carbon dioxide, produced by the yeast respiration, causes the bread to rise;
-the bread is then baked.
In the production of yoghurt:
-a starter culture of bacteria is added to warm milk;
-the bacteria ferment the milk sugar (lactose), producing lactic acid;
-lactic acid causes the milk protein to form a solid material.
Brewing
-Yeast respires sugar to form ethanol and CO2
-The source of sugar is usually fruit juice or grain
-The ethanol makes the drink alcoholic; carbon dioxide gives the drink its fizz. The process is called fermentation
This is all we need to know By the way
-
Silly question:
Is Single-cell protein the name of the protein or the name of the bacteria (or the process)??
-
Protein :D
-
nid404
Thank you SO much!!!
-
pleasure is mine ;D
-
A NOTE TO ALL SF USERS :
In less than 24 Hours the Physics Paper 6 and other IGCSE examinations will commence. Once this examination is over:
a) You MUST WAIT 24 HOURS before any discussions can take place.
b) ALL DISCUSSIONS must be held in the following thread : https://studentforums.biz/index.php/topic,7273.0.html
Good Luck to You All.
-
Protein :D
Thanks :D
-
Silly question:
Is Single-cell protein the name of the protein or the name of the bacteria (or the process)??
lol .. even i was a lil confused about it before my prelims .. :P
-
lol .. even i was a lil confused about it before my prelims .. :P
hheehhe :D We all have these kinds of doubts ;)
-
hheehhe :D We all have these kinds of doubts ;)
By the way tht was 3 months ago ..!!
-
hey can anyone tell me where i can get bio AS edexcel unit 3b pastpapers from june 06 onwards
with markschemes
thank you
-
hey can anyone tell me where i can get bio AS edexcel unit 3b pastpapers from june 06 onwards
with markschemes
thank you
https://studentforums.biz/index.php/board,94.0.html (https://studentforums.biz/index.php/board,94.0.html)
I think you should ask in the link above cuz here is Cambridge not Edexcel
-
any tips for the paper 6 chemsitry next week :D?
-
Past papers.
-
good notes for chem
http://www.drbateman.net/asa2sums/sum5.5/sum5.5.htm#boiling under reflux
-
good notes for chem
http://www.drbateman.net/asa2sums/sum5.5/sum5.5.htm#boiling under reflux
a bit complicated for ig :/
-
a bit complicated for ig :/
ohh im sorry
i should have specified
this was for chem AS :/
sorry
-
http://www.freeexampapers.us/IGCSE/Biology/CIE/2006%20Nov/0610_w06_qp_6.pdf (http://www.freeexampapers.us/IGCSE/Biology/CIE/2006%20Nov/0610_w06_qp_6.pdf)
I plotted the points and everything but i don't know how to join them especially that my x axis starts from 0-10-20, so i don't know if i should extend the curve to 0 or not. Also after i extend it to 168, how can i make it decrease to 120??? Can u plz draw :)
Thanks in advance :D
-
Insoluble compounds.
Chlorides, bromides, iodides of silver and lead.
Sulfates of Calcium, barium and lead.
All hydroxides except those of group 1
All carbonates except those of group 1
Metal oxides except group 1 and 2s.
--
Flammable : Most alkanes, kersoene, petrol and naturally occurring oils.
Opps.
Should be :
All carbonates except those of Group I and Ammonium.
All hydroxides except those of Group I, Strontium, Calcium and Barium
-
So, i got my Alternative to practicle paper coming up soon after the I.T exam. Wanted to say what we should focus on other than solving past papers? Of course solving gets you into the groove but knowing the meat of the paper (As in from which chapter they bring the questions from) is the most important thing. Or maybe notes for paper 6?
Thanks!
-
in paper 6 when we do the measure the temperature thing which is on almost evry past paper..hhow many (d.p) or sigi fig?
-
It depends on on the question .. precisely the diagram which may hav a scale of a whole number or maximum to 1dp .. measuring vol/temperature is usually 2-3 s.f.g (lik 2-3 digits .. 150cm3 or 37 oC ect .. )
-
So, i got my Alternative to practicle paper coming up soon after the I.T exam. Wanted to say what we should focus on other than solving past papers? Of course solving gets you into the groove but knowing the meat of the paper (As in from which chapter they bring the questions from) is the most important thing. Or maybe notes for paper 6?
Thanks!
i need help in this too -_-
-
I posted on the wrong thread. DAMN
-
You might consider doing the chapter acids, bases and salts .. learn solubility and insolubility of specific compounds .. LEARN the chemical tests for anions and cations as well as gasses .. chromatography .. have some ideas for 'rate of reaction', 'measuring rate', 'types of reactions' 'endothermic/exothermic' .. also know basic apparatus used in a laboratory .. sadly i havnt solved many paper 6 s in chemistry .. i dont hav much idea about them tho .. =\
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You might consider doing the chapter acids, bases and salts .. learn solubility and insolubility of specific compounds .. LEARN the chemical tests for anions and cations as well as gasses .. chromatography .. have some ideas for 'rate of reaction', 'measuring rate', 'types of reactions' 'endothermic/exothermic' .. also know basic apparatus used in a laboratory .. sadly i havnt solved many paper 6 s in chemistry .. i dont hav much idea about them tho .. =\
I think you hitted the nail on the chapters. I also were thinking about reading these chapters for P6. I guess i'll solve and revise those chapters, but first, lets finish from I.T tomorrow!
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You might consider doing the chapter acids, bases and salts .. learn solubility and insolubility of specific compounds .. LEARN the chemical tests for anions and cations as well as gasses .. chromatography .. have some ideas for 'rate of reaction', 'measuring rate', 'types of reactions' 'endothermic/exothermic' .. also know basic apparatus used in a laboratory .. sadly i havnt solved many paper 6 s in chemistry .. i dont hav much idea about them tho .. =\
thx dude ....my tutor said that we should solve as much past papers as we can for paper 6 so that we do well an feel confident ,u kno ...
i ahve english ..got any ideas how i study for it ?
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thx dude ....my tutor said that we should solve as much past papers as we can for paper 6 so that we do well an feel confident ,u kno ...
i ahve english ..got any ideas how i study for it ?
Focus and read stories. Know as much words as possible for english which is by reading or just listning to a news forcast or a movie. Not only that but try to train on how to write a letter, essay .etc Take your time in reading the comprehensions and don't rush, also, check your paper when you finish 10000 times for spelling mistakes and punctuations.
English is very easy, dont worry. The only problem is that its a very long exam so your hands may sore from all the writing. I found the listening to be much more confusing than writing. For listening you need the ultimate focus and concentration.
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give 2 observation during fermentaion
1. buubbles and effervescence of a colourless gas ( CO2)
2. Mixture become cloudy ( because they multiply ) true? <-----------------????
also i can say heat is given out right ?
-
I am not confident if that would be an observation. You can't see heat. Observation is something you see with your naked eye...something you smell, test for. you can feel heat, but in this case it ain't much to be counted as an observation
yes you will see a suspension
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NEED HELP
MAY JUNE 1999. QUESTION 5 ..all questions please.. from (b) 1
S.O.S A.S.A.P
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/1993-2003/ChemistryExamP61993-2003.pdf
PAGE 142
ALSO A DOUBT :
does NAOH produec more energy with SULFURING ACID THAN WITH HCL??
-
It's taking time to load..hold on
-
cheers tyt
-
This is taking a long time.
Just take a snapshot of the question and attach it here..
-
its takin years to upload.. :/ nvm soory to bother you..ill upload it later and you can check it out anytime you want..thx anyway
-
just copy paste it then...You're not bothering me...no worries. :)
-
just copy paste it then...You're not bothering me...no worries. :)
http://img15.imageshack.us/gal.php?g=50781755.png
too hard to read .. :/
-
guys here i have got it and here is a snapshot of it...::
these are all the questions for question 5
and it's clear to read..:)
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guys here i have got it and here is a snapshot of it...::
these are all the questions for question 5
and it's clear to read..:)
::) how can i thank you !? :-* :P
-
::) how can i thank you !? :-* :P
hey it's no need to thank it's my pleasure that i was able to help you guys..:) :D :D :D
:)
-
Another questionS
Does NaOH prod. more heat with H2SO4 than wth HCL?
Does Group 1 and group 2 form colourless solution ?
cz i saw an analysis question..A CALCIUM SALT ( solutrion ) : COLOURLESS . i wrote white..
Why as u increase the length of an alcohol chain you do not need to burn as much fuel to release the same amoutn of energy?
-
I'm a lil busy....can u post the temp differences till then...
-
first table
EXP 1 8
EXP 2 8
EXP 3 8
EXPT4 16
SECOND TABLE
TEMP DIFF IS 5
-
b) i) state the obv. Just write exp 1 and 3 give the same temp change.
ii) Twice the change in expt 4
-
yes yes i kno those. Go on until the end of the question. im stuck at every question after those 2 :P
-
d) ii) A difference in temp change because of different conc of acid prolly.. cause usually the heat of neutralization is constant for any neutralization.-57kj/mol
e) After an hour it temp will fall back to the initial room temp. that is because the heat will be lost to the surrounding. The mixture will begin to cool
f) greater accuracy could be obtained by using a burette to take measurements.
-
d) ii) A difference in temp change because of different conc of acid prolly.. cause usually the heat of neutralization is constant for any neutralization.-57kj/mol
e) After an hour it temp will fall back to the initial room temp. that is because the heat will be lost to the surrounding. The mixture will begin to cool
f) greater accuracy could be obtained by using a burette to take measurements.
for d 2 ) the asnweer in past paper is DOUBLING REACTION RELEASES DOUBLE OF ENERGY ..makes any sense to you?
i understood ur answer thx tho
and can you go till g +
-
okay...doubling reaction? i don't see the reaction being double :-\
anyway
g) 1 shows greater change because total volume of reactants is lesser
H=mcdeltat
mass is proportional to the volume...greater mass, lower Temp change
-
h) temp change will be lower
heat is contained in a greater volume of liquid.
Same theory as above
-
I see hmm...i just dont get where the heat goes away to..? the heat is absorbed by the "more " volume of the liqiuid??
By the way ill give u 1+ rep..but after 2 hours cz i just gave some1 :P thx for ur time and help
hmm answr for h) is wrong ... the asnwer is
temp rise is 16 ( double )
explanation : complete neutralisation takes place ..doubling te temp change as exp 1 not all acid was neutralised.. (understandable )
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lol...heat doesn't go away...it's just spread over a larger volume. You tell me will a larger volume of water heat faster or a lower volume?
really...then maybe i got the question wrong. If you understood the answer for h, i won't have to go through the whole thing again...lol...sorry...it's just that im doing mechanics alongside...
+rep not really required..but thanks..lol
-
hehe thanks :D and mechanic :o :o :o :o :o goodluck
and last thing :P
Another questionS
Does NaOH prod. more heat with H2SO4 than wth HCL?
Does Group 1 and group 2 form colourless solution ?
cz i saw an analysis question..A CALCIUM SALT ( solutrion ) : COLOURLESS . i wrote white..
Why as u increase the length of an alcohol chain you do not need to burn as much fuel to release the same amoutn of energy?
ill dissapear after this
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All neutralization reaction have the same energy released...-57KJ/mol
colorless solutions...?? like what as hydroxides, salts..if salts...which salts.?? calcium carbonate is insoluble
And to your last question...well...i didn't quite get what ur asking...cause does this mean there are more OH groups..or only the no of hydrocarbons increased?
lol u needn't disappear...someone will always help you out here
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1.ok thats very helpful ..all neut haev same energy release! new fact
anyway
2.yea true ..stupid question from me..not concentrating..hmm i must have read the questing in a wrong way ...nvm
3 u kno the experiment to check which alcohols gives out more energy?
where you put the alcohols in a spirti burner..then heat the water in a copper can to a specific temperature.. and then weigh the masses of the spirit burner. etc..
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it says ..solution C has a calcium salt .identify the colour of solution C
does solution mean its colourless?
-
I gave my igs last year...i don't remember questions like that dude...:P
-
lol
paper 6 ananlysis :P anyway i get it cheers ::)
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lol i meant post the question....cause i don't remember them....if u tell me 'spirit question' im not going to know what u r talkn abt. I don't memorize past papers.. ::)
post the question ill answer
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http://www.freeexampapers.us/IGCSE/Biology/CIE/2006%20Jun/0610_s06_qp_6.pdf (http://www.freeexampapers.us/IGCSE/Biology/CIE/2006%20Jun/0610_s06_qp_6.pdf)
Q3)a)ii) I understand that i have to do proportions, but what should i do next?? draw the woodlice or shade or what??
Thanks ;D
-
http://www.freeexampapers.us/IGCSE/Biology/CIE/2006%20Jun/0610_s06_qp_6.pdf (http://www.freeexampapers.us/IGCSE/Biology/CIE/2006%20Jun/0610_s06_qp_6.pdf)
Q3)a)ii) I understand that i have to do proportions, but what should i do next?? draw the woodlice or shade or what??
Thanks ;D
draw the piechart using this formula
average/total average*360
use this angle and measure the degrrees on the piece chart with a protracter. than label each segment, no shading
-
Thanks man :D ;D
-
Whats the difference between electrolysis and cells?
And. When you burn for example. ETHANOL ..AND BUTANOL till the temperature of a beaker filled with water reaches 50 * C. You burn less mass of butanol to obtain same temperature rise!. Why is that?
-
more bonds are there , and more energy is given out
-
electrolysis is a process involving decomposition of an iconic compound using electrical energy .. if u use 'inert' electrodes like carbon .. if u change the electrodes to say copper, it tends to take part in the 'reaction' (electrolysis) .. you can purify copper with using copper electrodes .. u tht process too ??
making cells or batteries is slightly different .. in alkaline batteries (zinc carbon batteries) the positive electrode is manganese oxide and the negative electrode is zinc .. note tht these metals act as electrodes and an electrolyte used may be an alkali (sodium hydroxide)
Butanol has a larger chain compared to ethanol .. due to this fact more energy is released in the process of 'burning' of butanol ..
-
electrolysis is a process involving decomposition of an iconic compound using electrical energy .. if u use 'inert' electrodes like carbon .. if u change the electrodes to say copper, it tends to take part in the 'reaction' (electrolysis) .. you can purify copper with using copper electrodes .. u tht process too ??
making cells or batteries is slightly different .. in alkaline batteries (zinc carbon batteries) the positive electrode is manganese oxide and the negative electrode is zinc .. note tht these metals act as electrodes and an electrolyte used may be an alkali (sodium hydroxide)
Butanol has a larger chain compared to ethanol .. due to this fact more energy is released in the process of 'burning' of butanol ..
I get the alcohol question..but hmm
to make things clearer about electrolysis..pretend you get assked in an exam..What is the difference bettween electrolysis and cell?
i know 1 . Electrolysis converts electrical to chemical and cells form chemical to electrical ?? <--? right??
what else?
-
Cells produce electrical energy while electrolysis uses electricity to decompose compounds.
-
Also in electrolysis its Metal in cathode and non metal at anode while in cell its the more reactive in cathode and less reactive on anode...
-
im not so sure about "Electrolysis converts electrical to chemical "
-
im not so sure about "Electrolysis converts electrical to chemical "
ill find out in a minute :P ill be bothered to open the book and check ! ill jot down all the differences then ..its a common question in IG realy
-
i'll not check then .. im too lazy now to fetch my book .. =P
-
why do you think i asked the question on the site in the first place :-X :D
-
LOL .. XD
-
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_qp_6.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_qp_6.pdf)
5)c) It says that u have to add nitric acid on the salt... Wait a minute... can an acid react with a salt 0.o and if yes, under what conditions, bla bla
Thanks :D
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i think its a test for carbon dioxide .. check in the ms .. its fo 3 mks so effervescence seen and lime water turns milky .. dunno wats fo 3rd point ..
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So an acid CAN react with a salt.... but bases cant right?
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_qp_6.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_qp_6.pdf)
5)c) It says that u have to add nitric acid on the salt... Wait a minute... can an acid react with a salt 0.o and if yes, under what conditions, bla bla
Thanks :D
its not a salt..its a carbonate !!!!!!! so when u put in in acid...effervescent ..bubles of a collurless gas and solid decrease in size
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So an acid CAN react with a salt.... but bases cant right?
Whoa who told u tht ?? NaOH can react .. and so do other strong bases ..
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Also in electrolysis its Metal in cathode and non metal at anode while in cell its the more reactive in cathode and less reactive on anode...
Electrolysis : Negative ions from the electrolyte goes to Anode (Oxidation), Posititve ions from the electrolyte goes to Cathode (Reduction)
Cells : The more reactive metal undergoes Oxidation, whereas the Posititve ions from the electrolyte undergoes Reducation at the weaker metal electrode.
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can someone explain fuel cells with hydrgen?
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can someone explain fuel cells with hydrgen?
wel this is new in the syllabus right??
anyway
the main idea : producting electricity from hydrogen and oxygen adn the product being water!!
Consists of a chamber with a POROUS ANODE AND A POROUS CATHODE. AND IN BETWEEN IS THE ELECTROLYTE ( conc. KOH aq )
Hydrogen is pumped towards the ANODE (- ) and oxygen is pumped towards the CATHODE ( +) ..the electrolyte becomes ELCTROLYSED ..
reacion at ANODE H2 + 2OH ---> 2H2O + 2e-
at cathode : O2 +2H2O + 4e- ---> 4OH-
overall reaction H2 + O2 ---> H20
By the way ..electrode cotain nickel catalyst
Doesnt make any sence to me to be honest..its something i drew from class and i learned by heart...if u understand it explain it to me ::) but trust me the material i just gave you ^ is 100% ..all you need to know ..but i dont understand anythign about it
i mean since when was teh anode - and cathode +???
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http://auto.howstuffworks.com/fuel-efficiency/alternative-fuels/fuel-cell2.htm
this helps explain !...but the anode reaction adn cathode reaction is LIES? or is it that mine is wrong ? hmm now im confused ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? >:(
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Fuel cell
These are Voltaic cells in which the reactants are continuously supplied to the electrodes. These are designed to convert the energy from the combustion of fuels such as H2, CO, CH4, etc. directly into electrical energy. The common example is hydrogen-oxygen fuel cell as described below,
In this cell, hydrogen and oxygen are bubbled through a porous carbon electrode into concentrated aqueous sodium hydroxide or potassium hydroxide. Hydrogen (the fuel) is fed into the anode compartment where it is oxidised. The oxygen is fed into cathode compartment where it is reduced. The diffusion rates of the gases into the cell are carefully regulated to get maximum efficiency. The net reaction is the same as burning of hydrogen and oxygen to form water. The reactions are
At anode : 2 [ H2(g) + 2OH-] (aq) --->2H2O (I) + 2e-
At cathode : O2 (g) + 2H2O(I) + 4e- ---> 4OH- (aq)
Overall reaction : 2H2 (g) + O2 (g) ---> 2H2O (I)
Each electrode is made of porous compressed carbon containing a small amount of catalyst ( Pt, Ag or CoO ). This cell runs continuously as long as the reactants are fed.
(http://www.transtutors.com/userfiles/image/Navjeevan/electrode-potential1.JPG)
Advantages
(1) High efficiency : The fuel cells convert the energy of a fuel directly into electricity and therefore, they are more efficient than the conventional methods of generating electricity on a large scale by burning hydrogen, carbon fuels. Though we expect 100 % efficiency in fuel cells, so far 60 – 70% efficiency has been attained. The conventional methods of production of electrical energy involve combustion of a fuel to liberate heat which is then used to produce electricity. The efficiency of these methods is only about 40%.
(2) Continuous source of energy : There is no electrode material to be replaced as in ordinary battery. The fuel can be fed continuously to produce power. For this reason, H2 - O2 fuel cells have been used in space crafts.
(3) Pollution free working : There are no objectionable byproducts and, therefore, they do not cause pollution problems. Since fuel cells are efficient and free from pollution, attempts are being made to get better commercially
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Fuel cell
These are Voltaic cells in which the reactants are continuously supplied to the electrodes. These are designed to convert the energy from the combustion of fuels such as H2, CO, CH4, etc. directly into electrical energy. The common example is hydrogen-oxygen fuel cell as described below,
In this cell, hydrogen and oxygen are bubbled through a porous carbon electrode into concentrated aqueous sodium hydroxide or potassium hydroxide. Hydrogen (the fuel) is fed into the anode compartment where it is oxidised. The oxygen is fed into cathode compartment where it is reduced. The diffusion rates of the gases into the cell are carefully regulated to get maximum efficiency. The net reaction is the same as burning of hydrogen and oxygen to form water. The reactions are
At anode : 2 [ H2(g) + 2OH-] (aq) --->2H2O (I) + 2e-
At cathode : O2 (g) + 2H2O(I) + 4e- ---> 4OH- (aq)
Overall reaction : 2H2 (g) + O2 (g) ---> 2H2O (I)
Each electrode is made of porous compressed carbon containing a small amount of catalyst ( Pt, Ag or CoO ). This cell runs continuously as long as the reactants are fed.
(http://www.transtutors.com/userfiles/image/Navjeevan/electrode-potential1.JPG)
Advantages
(1) High efficiency : The fuel cells convert the energy of a fuel directly into electricity and therefore, they are more efficient than the conventional methods of generating electricity on a large scale by burning hydrogen, carbon fuels. Though we expect 100 % efficiency in fuel cells, so far 60 – 70% efficiency has been attained. The conventional methods of production of electrical energy involve combustion of a fuel to liberate heat which is then used to produce electricity. The efficiency of these methods is only about 40%.
(2) Continuous source of energy : There is no electrode material to be replaced as in ordinary battery. The fuel can be fed continuously to produce power. For this reason, H2 - O2 fuel cells have been used in space crafts.
(3) Pollution free working : There are no objectionable byproducts and, therefore, they do not cause pollution problems. Since fuel cells are efficient and free from pollution, attempts are being made to get better commercially
wooooow cheeeeeers but a few questions :P
how is anode the negative and cathode posotive :/?
and where does OH- come from? from electrolyte is it?
adn what happens first...the anode from 2h2o + 2e- and it gives thhose electrons to the cathode to reducs the oxygen ?? what is the process exactly ?
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wooooow cheeeeeers but a few questions :P
how is anode the negative and cathode posotive :/?
and where does OH- come from? from electrolyte is it?
adn what happens first...the anode from 2h2o + 2e- and it gives thhose electrons to the cathode to reducs the oxygen ?? what is the process exactly ?
same question
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http://americanhistory.si.edu/fuelcells/basics.htm
This should help
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i have a fair and simple explanation..
HYDROGEN JOIN WIHT THE OH- to form h2o + 2e-...this gives out electrons..which eneter the electrode makin it NEGATIVE!!!!!!
^ this explains the equation an anode.....
Electrons go to the other elctrode WHERE OH- IS MADE ( thts why its a non ending process ! 8))...at the other electrode O2 + H20 + 4E- to form OH-...why is is postovi ..cz your takin elecron away from it... cheers!
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I am afraid that the suggested explainations above are incorrect.
Anode : H2 ---> 2H+ + 2e-
Cathode : O2 + 2H2O + 4e- ---> 4OH-
Overall reaction : H+ + OH- ---> H2O
2H2 + O2 ---> 2H2O
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I am afraid that the suggested explainations above are incorrect.
Anode : H2 ---> 2H+ + 2e-
Cathode : O2 + 2H2O + 4e- ---> 4OH-
Overall reaction : H+ + OH- ---> H2O
2H2 + O2 ---> 2H2O
i understand the first 1
but the cathode...? where does the 2h2o come from?
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i understand the first 1
but the cathode...? where does the 2h2o come from?
same question
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http://www.youtube.com/watch?v=OmVnIIgDA7o&feature=PlayList&p=9D48A68D6EBE2C5B&playnext_from=PL&playnext=1&index=8
watch this...
It may seem stupid :P But it'll help you understand the mechanism
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still dont understand
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I'll have to look for my chem guide...I gave my igs last year...so ill really have to look for the books...
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its not a salt..its a carbonate !!!!!!! so when u put in in acid...effervescent ..bubles of a collurless gas and solid decrease in size
OMG LOL srry i got confused :-[ ;D
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i understand the first 1
but the cathode...? where does the 2h2o come from?
I'm not sure, but i think it might be that when u add oxygen and hydrogen they react. This ofc only if the cathode and anode aren't seperated (like a wall between them)
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still dont understand
At negative
Hydrogen loses electrons to the OH- ions .. its oxidised
2H2 (g) + 4OH- -----> 4 H2O (l) + 4 e-
At positive
The electrons are accepted by oxygen molecules
Oxygen is reduced to OH- ions
O2 (g) + 2H2O + 4e- ----> 4OH-
Adding two half equations :
2H2 (g) + O ---> 2H2O (l)
i think thts wat nid has explained before..
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I'm not sure, but i think it might be that when u add oxygen and hydrogen they react. This ofc only if the cathode and anode aren't seperated (like a wall between them)
Cathode and Anode are separated by a penetrable membrane which enables Hydrogen and Oxygen to interact.
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can somebody explain to me what is continuous and discontinuous variation??
i'm confused :-\
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1) nitrogen in air to nitrates: @artificial by haber
B natural by lightening
C biological by nodular bacteria and free living nitrogen fixing bacteria
2)fate of nitrates in the soil: @absorbed by the plant
B leached to rivers or lakes
C changed back to nitrogen in air by denitrifying bacteria
3)if it is absorbed plant eaten by animals then either plants or animal die so nitrogenous compound is changed tO AMMONIA in soil
4) the ammonia is changed back to nitrates by effect of nitrifying bacteria thn you go again to (2) to see its fate
i wish this help u understand it and get it ;) ;) ;D who wanted the nitrogen cycle
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frst the CONTINUOUS VARIATION IS DONE BY THE NATURE: HAVE INTERMEDIATES ,NO SHARP CUT BETWEEN CHAR , NOT CONTROLLED BY GENES (height,weight,.....)
scnd the DISCONTINUOUS VARIATION IS CONTROLLED GENETICALLY: SHARPCUT BETWEEN CHAR ( either boy or girl)(blue or brown eye)....,no inter mediates
tell me if u got it or not
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HAVE INTERMEDIATES ,NO SHARP CUT BETWEEN CHAR
SHARPCUT BETWEEN CHAR....,no inter mediates
tell me if u got it or not
mind explaining me this ??
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hey any suggestions for the chem practicals?
i suck at pracs :-\
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PAST PAPERS!!
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yeah but stuff like relation between concentration and volume...what test to carry out when they randommly ask for testing sumthing...
i dont get theses freaking things AT ALL! :|
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mind explaining me this ??
well it just have intermediates may be your height 176cm or 167 ,166 170.5 not fixed u r either 170 or 180...
thts the intermediates and sharpcut thing sharpcut is tht no intermediates got it?
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Actually i kno wats continuous and discontinuous jus the words "intermediates " and "sharpcut" is new to me ..
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yeah but stuff like relation between concentration and volume...what test to carry out when they randommly ask for testing sumthing...
i dont get theses freaking things AT ALL! :|
https://studentforums.biz/index.php/topic,7663.0.html
this might hlp!
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Mole number = Volume x Concentration.
The greater the concentration, not only that there will be more particles per dm^3 for collision, the product would increase proportionally ...
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frst the CONTINUOUS VARIATION IS DONE BY THE NATURE: HAVE INTERMEDIATES ,NO SHARP CUT BETWEEN CHAR , NOT CONTROLLED BY GENES (height,weight,.....)
scnd the DISCONTINUOUS VARIATION IS CONTROLLED GENETICALLY: SHARPCUT BETWEEN CHAR ( either boy or girl)(blue or brown eye)....,no inter mediates
tell me if u got it or not
yup n thx :D
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guys can u pls. check if this ones right !!
thanks .. q. 4 b)
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any 1 has m/j 98
if yes den plz answer q3 c & d
thnk u ::)
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any 1 has m/j 98
if yes den plz answer q3 c & d
thnk u ::)
what subject..?
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what subject..?
CHEM ;)
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CHEM ;)
p1 p3 or p6 :/
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p1 p3 or p6 :/
sorry p6
its like i m tooo tensed 4 chem :P
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o ..easy..
Look the product of Molten led iodide is
MOLTEN LEAD AND IODINE GAS RGHT..THE GAS EVAPORATES! but as you see ffrom the diagram teh MOLTEN LEAD is left in the tube..and is in contact with both electrodes..adn hey??? lead is a metal! conducts electricity !!! so it completes the ciricuit !!
and d ) since lead iodide is toxic..and a gas is produced..always do that in a fume cupbborad ..and wear safety goggles cz gas produced
By the way im doing the exam with you on the 18th goodluck and heere are some notes i wrote ..hope its useful
https://studentforums.biz/index.php/topic,7663.0.html
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o ..easy..
Look the product of Molten led iodide is
MOLTEN LEAD AND IODINE GAS RGHT..THE GAS EVAPORATES! but as you see ffrom the diagram teh MOLTEN LEAD is left in the tube..and is in contact with both electrodes..adn hey??? lead is a metal! conducts electricity !!! so it completes the ciricuit !!
and d ) since lead iodide is toxic..and a gas is produced..always do that in a fume cupbborad ..and wear safety goggles cz gas produced
By the way im doing the exam with you on the 18th goodluck and heere are some notes i wrote ..hope its useful
https://studentforums.biz/index.php/topic,7663.0.html
ya i was actually going thru dese notes
very HELPFUL i gav u a +rep :P :) ;)
GUDLUCK 2 U ASWELL
which invariant r u giving ????
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o ..easy..
Look the product of Molten led iodide is
MOLTEN LEAD AND IODINE GAS RGHT..THE GAS EVAPORATES! but as you see ffrom the diagram teh MOLTEN LEAD is left in the tube..and is in contact with both electrodes..adn hey??? lead is a metal! conducts electricity !!! so it completes the ciricuit !!
and d ) since lead iodide is toxic..and a gas is produced..always do that in a fume cupbborad ..and wear safety goggles cz gas produced
By the way im doing the exam with you on the 18th goodluck and heere are some notes i wrote ..hope its useful
https://studentforums.biz/index.php/topic,7663.0.html
n ya Thanks A LOOOTT
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N YA 1 more question wat are halides???? :P
i forgot =P
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no prob! and im not sure which vairiant im doin lol :P
halides are in group 7
F, CL , I etc..
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guys can u pls. check if this ones right !!
thanks .. q. 4 b)
anyone .. check my previous post ..
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ok ill do the question now
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o ..easy..
Look the product of Molten led iodide is
MOLTEN LEAD AND IODINE GAS RGHT..THE GAS EVAPORATES! but as you see ffrom the diagram teh MOLTEN LEAD is left in the tube..and is in contact with both electrodes..adn hey??? lead is a metal! conducts electricity !!! so it completes the ciricuit !!
and d ) since lead iodide is toxic..and a gas is produced..always do that in a fume cupbborad ..and wear safety goggles cz gas produced
By the way im doing the exam with you on the 18th goodluck and heere are some notes i wrote ..hope its useful
https://studentforums.biz/index.php/topic,7663.0.html
lol <3ed de way u xplained this part ;D
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ok ill do the question now
thanks .. jus wanna make sure im right .. ;)
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graph is perfectly fine but hmmm.. im not sure if the bars should be stuck together?
you should leave space between each 1 right?? or wrong ? nto sure but the graph is perfecty fine
and i kno it was hard to draw it on computer but u knew each line as .5? so urs was a bit inaccurate on computer but just making sure
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ur right .. ;) when i asked my dad he told me its more lik a histogram than a bar graph .. nyway thanks .. :)
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ur right .. ;) when i asked my dad he told me its more lik a histogram than a bar graph .. nyway thanks .. :)
In Chem and Bio, You HAVE to have space in between the bars, says the mark scheme.
So, that makes it DIFFERENT from a histogram where they're joined, and MORE LIKE a bar chart, where they're separate. :)
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ya thts wat i meant .. prolly u didnt hav a look at my previous post were i'd posted the doubt .. it looks lik a histogram .. it should hav been spaced .. thts wat i meant .. nvm
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can somebody tell me why is a food chain usually have fewer than five trophic levels?
it's in the syllabus...section IV
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and can somebody tell me why there is an increases efficiency in supplying green plants as human food and that there is a relative inefficiency , in terms of energy loss,in feeding crop plants to animals....
it's also in the sylllabus...section IV
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interpert simple chromatograms including the use R values
??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ???
urgently please fast
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can somebody tell me why is a food chain usually have fewer than five trophic levels?
it's in the syllabus...section IV
As you higher through trophic levels energy is lost. Eventually there wouldnt be sufficient energy for more trophic levels
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answer me fast please
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and can somebody tell me why there is an increases efficiency in supplying green plants as human food and that there is a relative inefficiency , in terms of energy loss,in feeding crop plants to animals....
it's also in the sylllabus...section IV
Have you got the question right...?
I think you mean why is it more efficient to eat the green plant than the animal, in which case answer would be that less energy is wasted by eating the plant than eating the animal..
-
interpert simple chromatograms including the use R values
??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ???
urgently please fast
-
and can somebody tell me why there is an increases efficiency in supplying green plants as human food and that there is a relative inefficiency , in terms of energy loss,in feeding crop plants to animals....
it's also in the sylllabus...section IV
it means that why there is an advantage in feeding on green plants directly rather than having animals fed (e.g. feeding maize to a cow) and consuming them
ans. less energy lost when plants directly consumed .. =)
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interpert simple chromatograms including the use R values
??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ???
urgently please fast
i had a presentation on it .. wait lemme check ..
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chromatography is when you put some spots on a line made of pencil -because ink dissolves- in a solvent where it spins and gives spots
the rf value is to see the distance moved by a spot by the distance moved by the solvent and each substance has a particular rf value so you can identify the substance by it
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HERE YOU GO .. ;)
enjoy .. :)
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Need chemistry paper 6 may june 2001 urgent !!
Email to thunder.rahul@hotmail.com
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thanx
-
go and check in the
http://www.xtremepapers.net/
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Nid, in meiosis, does duplication take place first or halving?
Thanks in advance
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there are other people on this forum as well .. =P =P jus jokin .. ;)
http://www.youtube.com/watch?v=D1_-mQS_FZ0
halving .. ;) want it detailed ??
-
can somebody tell me what is the purpose of thermal decomposition??
-
Have you got the question right...?
I think you mean why is it more efficient to eat the green plant than the animal, in which case answer would be that less energy is wasted by eating the plant than eating the animal..
i copied this from the syllabus...yes i got it right..u can check the syllabus section IV...
thats y i dont understand it...
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to decompose compounds which might be useful as elements or in simpler forms .. y do u ask ?
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it means that why there is an advantage in feeding on green plants directly rather than having animals fed (e.g. feeding maize to a cow) and consuming them
ans. less energy lost when plants directly consumed .. =)
thanks!now i understand... :D
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i copied this from the syllabus...yes i got it right..u can check the syllabus section IV...
thats y i dont understand it...
but u got it know right .. check my post on the previous page ;)
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thanks!now i understand... :D
ok sure .. ;)
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but u got it know right .. check my post on the previous page ;)
yeah,
thanks....
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to decompose compounds which might be useful as elements or in simpler forms .. y do u ask ?
just curious...we dont have to know it?
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ofc we do .. jus askin .. i thought u;d seen in some past paper or somethin .. because normally they dont ask such stuff .. =)
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I have a doubt and i've no idea from where i got this idea but please tell me if i'm right..
In most questions for paper 6 (chemistry) they ask what type of reaction occured. How do we know if a reaction is exothermic or endothermic if no information about temperature change is given? Also, are all reacctions with hydrogen as a by-product exothermic? What about water? There was a question: what reaction occurs when ammonium chloride reacts with water. I thought it was exothermic and so did my colleagues but the marking scheme says endothermic. Please explain!
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All combustion and neutralization reaction are exothermic.
When salts dissolve, an endothermic reaction occurs.
This is the general thing you need to know for igz
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combustion produces heat right .. ???
my sir had told me something vital about it .. i forgot !! :(
-
I have a doubt and i've no idea from where i got this idea but please tell me if i'm right..
In most questions for paper 6 (chemistry) they ask what type of reaction occured. How do we know if a reaction is exothermic or endothermic if no information about temperature change is given? Also, are all reacctions with hydrogen as a by-product exothermic? What about water? There was a question: what reaction occurs when ammonium chloride reacts with water. I thought it was exothermic and so did my colleagues but the marking scheme says endothermic. Please explain!
||Exothermic Reactions:
1) When Dilute hydrochloric acid reacts with sodium hydroxide solution a neutralistation reaction happens
2)All Displacement Reactions :
Mg + H2SO4 -----> MgSO4 + H2
3) Combustion
||Endothermic Reactions:
1) N2 + 02 -----> 2NO
(dunno what is it called but thats whats written in the book)
2)Thermal Decomposition:
Ca(OH)2 -----> CaO + H20
2Cu (NO3)2 ------> 2CuO + 4NO2 + O2
3) Melting of ice and evaporation of water
(yes, you probably thought it was exo like me, but it turned out to be endo)
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sorry exothermic...i edited my post
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All combustion and neutralization reaction are endothermic.
When salts dissolve, an endothermic reaction occurs.
This is the general thing you need to know for igz
arent combustion reactions exothermic? ???
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sorry exothermic...i edited my post
oops didnt see
sorry :)
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||Endothermic Reactions:
1) N2 + 02 -----> 2NO
(dunno what is it called but thats whats written in the book)
3) Melting of ice and evaporation of water
(yes, you probably thought it was exo like me, but it turned out to be endo)
LOL Nitrogen monoxide
i knew melting of ice and evaporation of water is endothermic .. !! =P
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How can melting and evaporation be exo :o
It's endo..
Reason---> It gains kinetic energy, which implies heat energy also increases. To melt a substance, you supply heat...heat is taken in from the surrounding.
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.. to overcome the inter-molecular force and the molecules are set free .. its by-heart .. lol =D
but who said its exo ??
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lol guess m srry for saying its exo xD ;D I just thought that it became hotter and so exo :P
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dont think too much !! lol .. joke =P
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nid404
can u please tell me wats all important in these chaps:homeostasis...and hormones...and drugs(which ones and wat all about them)??
i jus want u tell all thts important in brief...and explain sum hard stuff..like u did about tht lymphatic system previously!!...Thanks plz reply soon!!
tell also which papers to do?.....and which tests and expeiments to remember..like really nicely!!!...=D
thnksss sooooooo much!!..i hope u help me!!.... :)
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i hv a query:
what solvents can u use in chromatography and does the solvent u use depend on what u r extracting?
eg. in this question from O/N 2009 chem p6
7) Leaves from trees contain a mixture of coloured pigments which are not soluble in water. A
student was given these two instructions to investigate the pigments in the leaves.
1. Crush some leaves to extract the coloured pigments.
2. Use the liquid extract to find the number of coloured pigments in the leaves.
(a) What would the student need in order to effectively carry out instruction 1?
the ms says pestle/mortar/solvent/sand (any three)
ignore water and/or heat
why ??? ???
Thanks
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yes the solvent always deends on what u are extracing.. and in this case its not water ! cz it tells you in the question that its isnoluble in water..so what you say is..use suitable solvent which dissolves the pigments..and explaint hte chromatofrphy process..
it says ignore water and heat cz its insoluble in water..altho i think heating with the SUITABLE SOLVENT should work..but anyway if u write that you dont get marked down i guess..so pestle adn morart is enough for crushing.
i hhave no idea what teh sand is for ? probably like filtering water...you put pigments in solvent and put it in sand and the insoluble stuff wont penetrate?
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??? ??? ??? ??? ??? ???
PAPER 6 OCT/NOV 2004 QUESTION 5..
5 (B) please .
links :
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2004%20Nov/0620_w04_qp_6.pdf
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2004%20Nov/0620_w04_ms_6.pdf
Explain HCL?
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for b when ammonium chloride is warmed, it gives out ammonia and HCl
NH4Cl----> NH3 + HCl
do you get it now...?
NH3 turns red litmus blue(basic)
HCl turns blue litmus red (acidic)
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how can boiling something wid water <eg: jam> extract the colour?????
confusing
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how will u noe hw many dots 2 make in chromatography?????
bcoz in m/j q2 d) 2006 i made 2 bt in ms its 3 y??? n hw????
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how will u noe hw many dots 2 make in chromatography?????
bcoz in m/j q2 d) 2006 i made 2 bt in ms its 3 y??? n hw????
1 dot at the origin + n dots (where n is the no of different substances in the chemical mixture)
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1 dot at the origin + n dots (where n is the no of different substances in the chemical mixture)
but they didnt tel in this ppr
????
here is the ques:
A sample of orange fruit jam was investigated to check the three colourings present.
Step 1 The jam was boiled with water.
Step 2 The mixture was filtered.
Step 3 The filtrate was concentrated.
Step 4 The concentrate was analysed by chromatography.
(a) What was the purpose of Step 1?
[1]
(b) Why was the mixture filtered?
[1]
(c) How was Step 3 carried out?
[1]
(d) Draw a diagram to show the possible paper chromatogram obtained in Step 4.
jus answer part d dat hw did u noe dat 3 dots r presnt
THANX
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@nid404
but see how do u know 3 dots..specifically...because in tht paper..its just said tht its a jam...and we r doing chromatagrophy of its mixture..after these steps:
2 A sample of orange fruit jam was investigated to check the three colourings present.
Step 1 The jam was boiled with water.
Step 2 The mixture was filtered.
Step 3 The filtrate was concentrated.
Step 4 The concentrate was analysed by chromatography.
then after Q1 a,b,c,......
..its d they ask: Draw a diagram to show the possible paper chromatogram obtained in Step 4.
so can u tell us if they just meant to make it maximum 3 (like not less than 3)...or its only ryt for specifically three dots
....and is the line dot or spot counted as 1??
Thanks....do reply
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OMG i got it...sorry..thts so dumbo of me!!..got it!!
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@nid404
but see how do u know 3 dots..specifically...because in tht paper..its just said tht its a jam...and we r doing chromatagrophy of its mixture..after these steps:
2 A sample of orange fruit jam was investigated to check the three colourings present.
Step 1 The jam was boiled with water.
Step 2 The mixture was filtered.
Step 3 The filtrate was concentrated.
Step 4 The concentrate was analysed by chromatography.
then after Q1 a,b,c,......
..its d they ask: Draw a diagram to show the possible paper chromatogram obtained in Step 4.
so can u tell us if they just meant to make it maximum 3 (like not less than 3)...or its only ryt for specifically three dots
....and is the line dot or spot counted as 1??
Thanks....do reply
*slap on head*
Thanks a loot
rofl
:P
=D
ya i saw it
-
OMG i got it...sorry..thts so dumbo of me!!..got it!!
sree tok the rong quote
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OMG i got it...sorry..thts so dumbo of me!!..got it!!
oh hey hamza
rofl same doubt haan
copy cater
jk=P
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hi...6394....lol not copycater!!!
we r doin the paper together!!!...u see!!!
so oviously watever we didnt undertsand!!...we both ask on the forum..lol
..hehe.....Thanks nid404 anywz!!!
;D
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hi...6394....lol not copycater!!!
we r doin the paper together!!!...u see!!!
so oviously watever we didnt undertsand!!...we both ask on the forum..lol
..hehe.....Thanks nid404 anywz!!!
;D
ok lts stop wasting tym tel me hw did u do dat graph ??????
increasing iis from the readings we hve got bt wat abt dec.
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heyyyy
nid404....canu pleease tell me...watever is important for bio ppr6??...like PLZ tell which CHAPTERS??????
....and i need u to tell tht wats important in homeostasis...hormones and drugs..like which (hormones and drugs)......like how u have explained so nicely about tht lymphatic system previously...do explain me 2 !!...atleast briefly..but do putline the really imortant things.
.....Thanks SOO MUCH!!!!...awaitin ur reply!!
... :D.... :)
-
heyyyy
nid404....canu pleease tell me...watever is important for bio ppr6??...like PLZ tell which CHAPTERS??????
....and i need u to tell tht wats important in homeostasis...hormones and drugs..like which (hormones and drugs)......like how u have explained so nicely about tht lymphatic system previously...do explain me 2 !!...atleast briefly..but do putline the really imortant things.
.....Thanks SOO MUCH!!!!...awaitin ur reply!!
... :D.... :)
i'll tell u what's impo in bio paper 6
1. the classification chapter
2.experiments on germination (effect of water,temp,oxgen on germination)
3.experiments on the factors of photosynthesis (light, carbon dioxide,temperature )
4.differences between monoct and dicot plants
5.labellings for a flower,a snail,a seed
6.u should kno what kind of imporvements to make in eeach experiment there is in the paper but reading the table and question twice cuz the answer is there .( i wanna tell u more but i am too busy to type more)
those r mostly what my tutor told me
gd luck ;)
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i'll tell u what's impo in bio paper 6
1. the classification chapter
2.experiments on germination (effect of water,temp,oxgen on germination)
3.experiments on the factors of photosynthesis (light, carbon dioxide,temperature )
4.differences between monoct and dicot plants
5.labellings for a flower,a snail,a seed
6.u should kno what kind of imporvements to make in eeach experiment there is in the paper but reading the table and question twice cuz the answer is there .( i wanna tell u more but i am too busy to type more)
those r mostly what my tutor told me
gd luck ;)
INSHAALLAH 2 UR SIGNATURE
:)
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any 1 help in q 3 d and e full part
plsss
<p6 chem m/j 2006>
-
Thanks "the golden girl".....
.......thts really helpful of u...
....and ya when u get type plz do.........tell me others too...ill keep checkin !!...Thanks!!!
:)
-
yes the solvent always deends on what u are extracing.. and in this case its not water ! cz it tells you in the question that its isnoluble in water..so what you say is..use suitable solvent which dissolves the pigments..and explaint hte chromatofrphy process..
it says ignore water and heat cz its insoluble in water..altho i think heating with the SUITABLE SOLVENT should work..but anyway if u write that you dont get marked down i guess..so pestle adn morart is enough for crushing.
i hhave no idea what teh sand is for ? probably like filtering water...you put pigments in solvent and put it in sand and the insoluble stuff wont penetrate?
the sand is used to help break the leaf cells so that the leaf extract comes out while crushing and you can carry out the chromatography
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||Exothermic Reactions:
1) When Dilute hydrochloric acid reacts with sodium hydroxide solution a neutralistation reaction happens
2)All Displacement Reactions :
Mg + H2SO4 -----> MgSO4 + H2
3) Combustion
||Endothermic Reactions:
1) N2 + 02 -----> 2NO
(dunno what is it called but thats whats written in the book)
2)Thermal Decomposition:
Ca(OH)2 -----> CaO + H20
2Cu (NO3)2 ------> 2CuO + 4NO2 + O2
3) Melting of ice and evaporation of water
(yes, you probably thought it was exo like me, but it turned out to be endo)
isnt bond formation exothermic?! because im quite sure bond breaking is exothermic. And if thats right then how is it that N2 + O2 ---> 2NO is endothermic becuase is a bond formation!
Are all reactions with water endothermic or exothermic?
-
I've got a question > Outline and explain the likely effects of deforestation? Thanks :D
-
for b when ammonium chloride is warmed, it gives out ammonia and HCl
NH4Cl----> NH3 + HCl
do you get it now...?
NH3 turns red litmus blue(basic)
HCl turns blue litmus red (acidic)
ooh i see ! thanks man
-
I've got a question > Outline and explain the likely effects of deforestation? Thanks :D
- No trees = No soil anchors which means the soil will just run off into rivers. Level of water in river rises .... floods happen.
- Carbon dioxide levels increase in the atmopshere
- Loss of habitat[/i]
I cant think of more right now :P
-
www.google.com =P
Less rain
Soil erosion
loss of trees, habitats, animal life
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isnt bond formation exothermic?! because im quite sure bond breaking is exothermic. And if thats right then how is it that N2 + O2 ---> 2NO is endothermic becuase is a bond formation!
Are all reactions with water endothermic or exothermic?
Bond breaking is endothermic because the molecules are using energy from the surroundings to 'break' their bonds.
Bond forming is exothermic because of a reason, which im not quite sure is relevant to IGs... two molecules start off at a higher energy. When they bond together, they become more stable and release energy.
-
I've got a question > Outline and explain the likely effects of deforestation? Thanks :D
Increased soil erosion
Increased global temperatures as CO2 increases
leading to increase sea levels
loss of habitat
desertification
-
Bond breaking is endothermic because the molecules are using energy from the surroundings to 'break' their bonds.
Bond forming is exothermic because of a reason, which im not quite sure is relevant to IGs... two molecules start off at a higher energy. When they bond together, they become more stable and release energy.
it is very relevant for igs infact!
imagine the melting point adn heating point graph http://www.gcsescience.com/Graph-Temperature-Time-Substance.gif
when water is melting heat energy is given into the molecules so they can seperate adn BRAKE..therefore you putting energy in..ENDOTHERMIC REACTION..! u use energy to brake the bonds and not to heat the water and so thats why the gradient is flat at melitng point..
now imagine the water vapour condensing !! at the boiling point..why is it flat? because it stops loosing heat for a while and that is becausse it is forming bonds !! formng bonds is exothermic..energy is released to form bonds !! tahts why temp stop rising !
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Thanks "the golden girl".....
.......thts really helpful of u...
....and ya when u get type plz do.........tell me others too...ill keep checkin !!...Thanks!!!
:)
ya , i'll do my best inshAllah.
-
i'll tell u what's impo in bio paper 6
1. the classification chapter
2.experiments on germination (effect of water,temp,oxgen on germination)
3.experiments on the factors of photosynthesis (light, carbon dioxide,temperature )
4.differences between monoct and dicot plants
5.labellings for a flower,a snail,a seed ,an insect
6.u should kno what kind of imporvements to make in eeach experiment there is in the paper but reading the table and question twice cuz the answer is there .( i wanna tell u more but i am too busy to type more)
those r mostly what my tutor told me
gd luck ;)
7.how to detect transpiration (place a plastic bag on the plant ,water will condense)
8.effect of cutting roots of a seedling (wilts when cut , when not cut is healthy and upright)
9.effect of cutting roots of a plants on it's water uptake
10.u gotta what a bill jar is and thatit's used for testin for breathing
11. test for the different scents of plants and the effect of it on attracting insects (i wanna describe the exp but it's too long and i'm busy . sooo google it or smthn , k?)
12.test for the effect of colour of petal of a flower on the attracting of insects (google this too! )
13.exp on pulse rate of a runner and person whose not doin excersice
14.testin of carbon dioxide, and oxgen
15.test of finding the reaction time of a person
16.tests abt the effect of auxin on phototropism, and Geotropism
later ;)
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yes the solvent always deends on what u are extracing.. and in this case its not water ! cz it tells you in the question that its isnoluble in water..so what you say is..use suitable solvent which dissolves the pigments..and explaint hte chromatofrphy process..
it says ignore water and heat cz its insoluble in water..altho i think heating with the SUITABLE SOLVENT should work..but anyway if u write that you dont get marked down i guess..so pestle adn morart is enough for crushing.
i hhave no idea what teh sand is for ? probably like filtering water...you put pigments in solvent and put it in sand and the insoluble stuff wont penetrate?
k Thanks
the sand is used to help break the leaf cells so that the leaf extract comes out while crushing and you can carry out the chromatography
o i c
yea that makes sense
Thanks :) +rep
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question 4 h <p6 chem 2006 o/n> can we ryt dat the initial emp shud be same
and abt room temp.
-
question 4 h <p6 chem 2006 o/n> can we ryt dat the initial emp shud be same
and abt room temp.
temp*
-
question 4 h <p6 chem 2006 o/n> can we ryt dat the initial emp shud be same
and abt room temp. for more accurate results
well i checked mark scheme and its no..to be honest every time i see measuring cyilnder..first thing that comes in my mind is use burette for more accurate measuring of liquind cz measuring cyl has 0.5 error and buret ha 0.05..
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WHENEVER The question refers to MEASURING CYLINDER, the answer to the improvements is ALWAYS, USING A BURETTE OR PIPETTE FOR MORE ACCURATE AND RELIABLE READINGS.
WHENEVER The question refers to TIME BEING TAKEN, the improvements are A DIGITAL STOP WATCH OR A DATA LOGGER.
:)
-
on 2007 p6 Q 4d
fast please
-
m/j or o/n?
-
on 2007 p6 Q 4d
for biology or chemistry
-
well i checked mark scheme and its no..to be honest every time i see measuring cyilnder..first thing that comes in my mind is use burette for more accurate measuring of liquind cz measuring cyl has 0.5 error and buret ha 0.05..
Thanks alot
-
adn oct/ nov or m/ j :P
-
on 2007 p6 Q 4d
for bio or chem
??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ???
reply me fast urgent reply
??? ??? ??? ???
-
WHENEVER The question refers to MEASURING CYLINDER, the answer to the improvements is ALWAYS, USING A BURETTE OR PIPETTE FOR MORE ACCURATE AND RELIABLE READINGS.
WHENEVER The question refers to TIME BEING TAKEN, the improvements are A DIGITAL STOP WATCH OR A DATA LOGGER.
:)
thnk u
data logger????
-
whats a colourimeter thing? is it like a data loggeror colour comparer
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i dont think colourimeter is a data logger .. colourimeter si a device measures the absorbance of wavelengths of light by a specific given solution. we hav it in our lab .. jus a small thing (looks lik a weighing scale without the plate) has a hole where a test tube can fit in .. had almost forgotten abt it !!
data logger records data over time .. thts wat i remember .. =\
-
whats a colourimeter thing? is it like a data loggeror colour comparer
is this "colourimeter" in som mark scheme or somthin
if yes plz tel which yr n blahla
if no ,den tel me where did u fynd this wrd
Thanks ;D :D ;) :P
-
Calorimeter is used for measuring the heat of chemical reactions or heat capacities
-
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2005%20Jun/0620_s05_qp_6.pdf
q5 3? why green ppt.
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Bond breaking is endothermic because the molecules are using energy from the surroundings to 'break' their bonds.
Bond forming is exothermic because of a reason, which im not quite sure is relevant to IGs... two molecules start off at a higher energy. When they bond together, they become more stable and release energy.
oh yea sorry by mistake i wrote exothermic for bond breaking and bond formation!
Anyway what you just said makes sense but then how is 2N + O2 ---> 2NO endothermic?! Since nitrogen is combining with oxygen shouldnt it be exothermic?!
-
on 2007 p6 Q 4d
for bio or chem
??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ???
reply me fast urgent reply
??? ??? ??? ???
oct nnov chemistry i a msorry
-
a colorimeter is a device used to measure the intensity of colour of a solution
u just need to know wen to use it for igcse
-
Calorimeter is used for measuring the heat of chemical reactions or heat capacities
They are talking about "Colorimeter" ur talking abt "Calorimeter" .. get it ??
-
i dont think colourimeter is a data logger .. colourimeter si a device measures the absorbance of wavelengths of light by a specific given solution. we hav it in our lab .. jus a small thing (looks lik a weighing scale without the plate) has a hole where a test tube can fit in .. had almost forgotten abt it !!
data logger records data over time .. thts wat i remember .. =\
-
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2005%20Jun/0620_s05_qp_6.pdf
q5 3? why green ppt.
Test for Copper(II)
That indicates tht the cation is Cu2+
green solution formed
dark blue solution formed
already given in the ques. ..
-
Bond breaking is endothermic because the molecules are using energy from the surroundings to 'break' their bonds.
Bond forming is exothermic because of a reason, which im not quite sure is relevant to IGs... two molecules start off at a higher energy. When they bond together, they become more stable and release energy.
It is also because the endothermic reaction needs more energy than the exothermic reaction...its a simple explanation. Every reaction has an endothermic and exothermic reaction involved, it just depends on which one requires more energy. When they say the reaction is endothermic, then OVERALL, the exothermic reaction needs less energy than the endothermic reation, and vice versa for exothermic reactions.
-
It is also because the endothermic reaction needs more energy than the exothermic reaction...its a simple explanation. Every reaction has an endothermic and exothermic reaction involved, it just depends on which one requires more energy. When they say the reaction is endothermic, then OVERALL, the exothermic reaction needs less energy than the endothermic reation, and vice versa for exothermic reactions.
oh i get it know! Thanks! =)
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oh yea sorry by mistake i wrote exothermic for bond breaking and bond formation!
Anyway what you just said makes sense but then how is 2N + O2 ---> 2NO endothermic?! Since nitrogen is combining with oxygen shouldnt it be exothermic?!
synthesis of N2 and O2 requires a lot of heat .. tht is why NO is formed in the presence of lightning naturally in the atmosphere
-
Test for Copper(II)
That indicates tht the cation is Cu2+
green solution formed
dark blue solution formed
already given in the ques. ..
I get that the dark blue is copper 2+ but isnt green ppt iron (II)?
-
Yea i kno even i was foxed by this one .. yes for Iron(II) its green ppt.., insouble in excess so solid B was added so prolly it had Fe 2+ i forcefully had look in the ms !! these kinda are always dicey .. i'll ask my sir .. abt it .. ;)
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Got two doubts.
Firstly, I'm looking for any Notes/Diagrams/Worksheets on The Chemistry Lab apparatus, where they are all listed and named. I have already tried the Resources at freepastpapers.com and it does not come n handy as the notes are missing a lot.
Secondly, the syllabus mentions that we should describe the test for aqueous zinc cations, it's not in my Collins Chemistry book, so can anyone elaborate on this test?
Plus, I have a tiny request, if anyone has any good links to some great notes for Paper 6 Chemistry, I have already checked the notes submitted in this forum as a post, but they're kind of confusing.
Thanks in advance...
-
have you checked this?
https://studentforums.biz/index.php/topic,7663.0.html
and zinc ations tes
white ppt which is soulbe in exces with naoh forming colourless soltuon
white ppt which is solube in excess with ammonia (aq) forming coourless soltn
-
Got two doubts.
Firstly, I'm looking for any Notes/Diagrams/Worksheets on The Chemistry Lab apparatus, where they are all listed and named. I have already tried the Resources at freepastpapers.com and it does not come n handy as the notes are missing a lot.
Secondly, the syllabus mentions that we should describe the test for aqueous zinc cations, it's not in my Collins Chemistry book, so can anyone elaborate on this test?
Plus, I have a tiny request, if anyone has any good links to some great notes for Paper 6 Chemistry, I have already checked the notes submitted in this forum as a post, but they're kind of confusing.
Thanks in advance...
lol @ kimo jesus i was jus goin 2 sugest this 1
rofl
n u jus postd it 1st
:P ;D =D
-
have you checked this?
https://studentforums.biz/index.php/topic,7663.0.html
and zinc ations tes
white ppt which is soulbe in exces with naoh forming colourless soltuon
white ppt which is solube in excess with ammonia (aq) forming coourless soltn
u posted it 1st ;)
-
colorimeter not calorimeter
its in the October/November 2005 Bio Paper 6-2(b) marck scheme
-
^^^Yes, I have.
So I'm left with those
Anyone else can help?
Firstly, I'm looking for any Notes/Diagrams/Worksheets on The Chemistry Lab apparatus, where they are all listed and named. I have already tried the Resources at freepastpapers.com and it does not come n handy
as the notes are missing a lot.
Plus, I have a tiny request, if anyone has any good links to some great notes for Paper 6 Chemistry, I have already checked the notes submitted in this forum as a post, but they're kind of confusing.
Thanks in advance...
-
lemme see if i can get some good links ..
if u hav checked the forum u might hav seen these ones too (which i've attached)..
-
colorimeter not calorimeter
its in the October/November 2005 Bio Paper 6-2(b) marck scheme
ah den i dnt need 2 worry lolz
i actually gt scard because i nvr heard of this wrd
=P
-
ah den i dnt need 2 worry lolz
i actually gt scard because i nvr heard of this wrd
=P
2 be more specific i dnt tak bio
-
Thanks VIN.
I actually saw that word document in the Resources but I thought they were missing a couple of things, but now with the diagram I guess that's all I need.
Edit:
If you can post those links it would be really great since I'm terribly desperate for some neat and comprehensible explanations...
-
https://studentforums.biz/index.php/topic,7663.0.html
https://studentforums.biz/index.php/topic,1593.0.html
http://www.chemactive.com/igcse_11_index.html
Check these
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Thanks for those...
And I have some more doubts.
For the Methods of purification mentioned in the syllabus, I wanted to summarize their uses, so can anyone proof read this to check if it's right and give me a brief description on each of these processes?
1- Filtration - Separating insoluble solids form liquid (Mixtures).
2- Crystallization - Separating solute from solution.
3- Distillation - Separating solvent from solution.
5- Fractional Distillation - Separating two liquids which are miscible.
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yup .. only thing u've typed crystallisation twice .. =P
How about Crystallisation - Separation of solvent from solute .. (check someone .. urs is right too)
also Fractional Distillation can be for more than two liquid too .. ;)
-
here
http://library.thinkquest.org/11430/research/techniques.htm
great site...
-
Thanks VIN for the help and nid for the link!
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For Paper 6 of Chemistry, you need to be able to:
-record readings from diagrams of apparatus
-describe, explain or comment on experimental arrangements and techniques
-complete tables of data
-draw conclusions from information given
-interpret and evaluate observations and experimental data
-describe tests for gases and ions, and/or draw conclusions from such tests
-plot graphs and/or interpret graphical information
-identify sources of error and suggest possible improvements in procedures
-suggest suitable techniques and apparatus for an investigation
Good Luck! :)
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i hav a couple of presentations here ..
i'll look for more ..
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i hav a couple of presentations here ..
i'll look for more ..
Thanks! (Y)
-
Hey, 1)What are the solvents that could be used in chromatography? + 2)What is meant by the terms excess and concentrated? -i know what do they mean but i dont know what 2 write :D- + 3)Why is crushing with sand helpful? + 4)What are the conditions for rusting, and explain what happenes + 5)while calculating the temperature difference, is it initial-final or final-initial? + 6)How can the purity of a liquid -such as ethanol- be checked? + 7)why ninhydrin and locating agents are used?
I know thats alot, but i'd appreciate any answer, Thanks :D
-
Hey, 1)What are the solvents that could be used in chromatography? + 2)What is meant by the terms excess and concentrated? -i know what do they mean but i dont know what 2 write :D- + 3)Why is crushing with sand helpful? + 4)What are the conditions for rusting, and explain what happenes + 5)while calculating the temperature difference, is it initial-final or final-initial? + 6)How can the purity of a liquid -such as ethanol- be checked? + 7)why ninhydrin and locating agents are used?
I know thats alot, but i'd appreciate any answer, Thanks :D
1) Water, or organic solvents, such as ethanol, depending what the dyes are soluble in.
2) -Excess refers to a substance in a greater quantity than the minimum quantity required to complete the reaction.
-A solution is concentrated when it contains a greater quantity/concentration i.e more solute than solvent.
3)To remove solid impurities, i guess. :S As it acts like a filtering sieve? :S ???
4)Oxygen and Water are required for rusting. i.e, HYDRATED IRON OXIDE (Fe2O3.xH20) forms, where x is the number of molecules of Water. This hydrated iron oxide is a reddish-brown layer, which when covering iron on steel, i.e corroding it, is specifically termed as rusting.
5)Final-Initial. Yes, the temp. diff. can be -ve. Examples of +ve and -ve graphs are there in past papers.
6) Umm, by checking the boiling point. Pure ethanol has a boiling point of 78 deg. C.
7) Often the amino acids or results of separating dies formed on the chromatogram ARE COLOURLESS/INVISIBLE, so to make them visible, so that they may be 'located', such agents are used.
Hope that helped. :)
-
5)while calculating the temperature difference, is it initial-final or final-initial?
if its a heating experiment, then final-initial
it your cooling something, initial-final
-
plzzz any one knw abt bio practical for may june 2010 paper 33???
-
DO NOT TRY TO CHEAT. THIS IS YOUR FIRST WARNING
-
Sorry to bother again, but I don't think I understood what she's trying to explain...
and zinc ations tes
white ppt which is soulbe in exces with naoh forming colourless soltuon
white ppt which is solube in excess with ammonia (aq) forming coourless soltn
May anyone explain this well and in details in proper English?
-
lol ::)
with NAOH with Ammonia ( aq)
test for zinc cations Forms white precipitate which is soluble White precipitiate which is soluble in excess forming
in excess forming a colourless solution a colourless solution
same resutls ::)
-
Sorry to bother again, but I don't think I understood what she's trying to explain...May anyone explain this well and in details in proper English?
well basically this means is dat zinc dissolve in excess sodium hydroxide to form a colourless solution
and zinc cations also dissolve in excess ammonia to give colourless solutiom
-
Get it ??
Still dont understand check the last page of the attached paper .. ;)
-
i ve jus got this ques
dere r 2 things we cn do if dyes formd on chromatogram are invisible
LOCATING AGENTS
N VIEWING IT IN UV LIGHT
-
i ve jus got this ques
dere r 2 things we cn do if dyes formd on chromatogram are invisible
LOCATING AGENTS
N VIEWING IT IN UV LIGHT
M I RYT
-
M I RYT
ny1 noes whethr m ryt
n ya wat is a spirit lamp" Use spirit burners to compare energy produced by different alcohols."
-
ohk 1 more ques
it came in my mocks :
why the mixture <i thnk it was a precipitate> shud b filtered and washed ??
FILTERED to remove insoluble impurities
why WASHED????
-
Ah right!
Thanks everyone for your replies...
They actually had the tests for everything back before at the end of their papers! So lucky, but I'm assuming their syllabus only uses tests for reference the way were going to use the periodic table...
-
ohk 1 more ques
it came in my mocks :
why the mixture <i thnk it was a precipitate> shud b filtered and washed ??
FILTERED to remove insoluble impurities
why WASHED????
washed to get rid of any remains of the liquids
-
how are we supposed to draw a diagram in bio p6 wen they giv u a pic???
i am really bad at drawing. does this mean i hv no hope 4 tht question?????
-
ny1 noes whethr m ryt
n ya wat is a spirit lamp" Use spirit burners to compare energy produced by different alcohols."
go on google type spirti burners adn see the image
what it is ..its like a bunsen burner but except that no gas pipe is attached to it.. there is liquid insde it..( alcohole ) which is flammable afcourse...so all you do is light it and the it burns !
and so what happens is we measure the mass of a spirt burner b4 an experiment and heat water to rise to certan temperature..and then we measure the new mass ..and we compare with other alcohols.etc
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ohk 1 more ques
it came in my mocks :
why the mixture <i thnk it was a precipitate> shud b filtered and washed ??
FILTERED to remove insoluble impurities
why WASHED????
washed to remove any soluble liquied that mght be stuck on it..its not washed really ..jsut MINIMAL AMOUNT OF COLD DISTILLED WATER IS PASSED OVER IT SO THE SOLULE MATERIAL THAT IS TRACED ON THE INSOLUBLE COULD LEAVE THRO THE FILTER PAPER
PS : i never heard of locating agent of uv rays..maybe right? but i never heard of it
-
go on google type spirti burners adn see the image
what it is ..its like a bunsen burner but except that no gas pipe is attached to it.. there is liquid insde it..( alcohole ) which is flammable afcourse...so all you do is light it and the it burns !
and so what happens is we measure the mass of a spirt burner b4 an experiment and heat water to rise to certan temperature..and then we measure the new mass ..and we compare with other alcohols.etc
Thanks for ur help
:P =D
-
washed to remove any soluble liquied that mght be stuck on it..its not washed really ..jsut MINIMAL AMOUNT OF COLD DISTILLED WATER IS PASSED OVER IT SO THE SOLULE MATERIAL THAT IS TRACED ON THE INSOLUBLE COULD LEAVE THRO THE FILTER PAPER
PS : i never heard of locating agent of uv rays..maybe right? but i never heard of it
Thanks agn
evn m nt sure bt i thnk last yr or sumthin my teachr was telin me abt this ;>
-
i know that locating reagent is right
but i am not sure about uv
-
no prob ..your questions are itnresting ::) + good revision :P
-
no prob ..your questions are itnresting ::) + good revision :P
lol Thanks :D
SO hw r u feelin nw
u wernt feelin wel b4 ryt??
-
yes uv can be used as a locating reagent but only in very rare conditions
-
lol Thanks :D
SO hw r u feelin nw
u wernt feelin wel b4 ryt??
im gr8 :P its just tht i have to do 8 more paper 6 for 2day ..boring :/ but this site encourages me raelly !! thx 4 askin :P
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washed to get rid of any remains of the liquids
Traces of the solution to be exact, in Percipitation you get an insoluble ppt and a solution, the ppt must be rinsed to remove the traces of the solution. As rinsing would attach water molecules to the percipitate, it then must also be placed in an oven to dry ...
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yes uv can be used as a locating reagent but only in very rare conditions
Thanks
bt still bttr 2 ryt abt the locating agent
;D ;D
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Thanks
bt still bttr 2 ryt abt the locating agent
;D ;D
just write locating reagent for ur answer ull get the mark
believe me i did my ig last year and dats all i learnt
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im gr8 :P its just tht i have to do 8 more paper 6 for 2day ..boring :/ but this site encourages me raelly !! thx 4 askin :P
i noe this syt is criously so hlpful!!!!!
;D
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Traces of the solution to be exact, in Percipitation you get an insoluble ppt and a solution, the ppt must be rinsed to remove the traces of the solution. As rinsing would attach water molecules to the percipitate, it then must also be placed in an oven to dry ...
thnk u ;DDD
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just write locating reagent for ur answer ull get the mark
believe me i did my ig last year and dats all i learnt
rofl at ur signature
:D;P
n Thanks
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haha lol
i know
and no prob
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guys experiments and procedures for p6 bio please dicuss themm also
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Hey for the Fractional distillation, the glass rods are to hold back the other liquids (the other liquids in the mixture which isn't their turn to evaporate) right??
Thanks ;D
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Hey for the Fractional distillation, the glass rods are to hold back the other liquids (the other liquids in the mixture which isn't their turn to evaporate) right??
Thanks ;D
well the longer the fractionating column the pureer the distillate and better seperations
actually other liquids condesce on those those rods whie the main liquid whose turn is to evaporates keeps evaporating..! but yea whth u said is right
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Thanks man :)
Another thing, Chromatography is to seperate solids dissolved in a solvent or liquids dissolved together??
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liquids dissolved together ;)
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cool 8) :D
omg next weak gonna be so boring 2 exams in one day and no day offs :S
I can't believe they are giving us a 10 days holiday just for Chem and Bio paper 6 >:( They should've divided it on the exams and let us finish earlier -.- :(
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liquids dissolved together ;)
huh ??? ??? ???
definition of crhomatography : used to seperate and identify a mixture of substance ( I.E SOLUBLE DYES sOLIDS) accodrding to their solubilty in the solvent adn their attraction to chrommatorgraphy paper :/
hw is it liquids dissolved toghert?
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hahahha see thats why i'm confused. A book saying this, and another saying that
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hahahha see thats why i'm confused. A book saying this, and another saying that
maybe he meant fractional distillation..most proabbly
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Chromatography can be the speration of any type of mixture.
Paper chromatography is used to separate solid mixtures, other chromatographies include gas and liquid.
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cool 8) :D
omg next weak gonna be so boring 2 exams in one day and no day offs :S
I can't believe they are giving us a 10 days holiday just for Chem and Bio paper 6 >:( They should've divided it on the exams and let us finish earlier -.- :(
Yeah! :@ :(
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I am panicking as Paper 6 chem is slowly approaching..I seem to have forgotten lots of stuff, and I need some tips and hints in solving paper 6 without going into unnecessary items which come only in paper3,etc
I'm also wondering if anyone got a link to a page which shows all lab apparatus labeled because in lots of papers there is questions on labeling them.
Help really appreciated, thanks in advance. :) :) :)
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Go through the posts on this (https://studentforums.biz/index.php/topic,7663.0.html) topic. It should help you revise.
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how to count number of stomata on underside of leaf
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Any tips for Chem Paper 6 tomorrow?!
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https://studentforums.biz/index.php/topic,7663.0.html
something i made for the paper 6 2mrw
goodluck ! ;D
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_6.pdf
can some1 help me with qeustion 4?
the graphs? can some1 draw them ?
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any 1 knows what are the chapter related to the chemistry paper 6
??? ??? ??? ??? ??? ??? ??? ??? ??? ???
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_6.pdf
can some1 help me with qeustion 4?
the graphs? can some1 draw them ?
Simply plot the points and join them freely..
points either have to be circled or you can use a cross(X)
What's the difficulty?
And whenever you draw a graph
Remember SLAP
Scale
Label
Axis
Plot
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Simply plot the points and join them freely..
points either have to be circled or you can use a cross(X)
What's the difficulty?
And whenever you draw a graph
Remember SLAP
Scale
Label
Axis
Plot
aw i meant the questions
the larger magnesium and iron powder
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I already revised the lab apparatus and the experiements. The only thing i don't know are the tests, does anyone know which chapter they are or better yet what is the chapter which needs to be the most focused one for tests? Also thanks, and good luck.
Don't worry people, its just P6 and its only for 20% so yeah.
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Remember SLAP
Scale
Label
Axis
Plot
such a nice one 8) ;D :D ;) :) :P ::)
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well if you dont make mistakes in this you can make all the mistaks you want on p3 ::)
i screwd up my paper 6 physisc ..lost 3 marks..now i feel tensioned about the paper 3 and 1 infact cz i have to ace paper 1!
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aw i meant the questions
the larger magnesium and iron powder
With magnesium pieces initial rate of reaction will be much lower, but it will plateau out on the same(over a longer period of time)
With iron powder, it will be still lower, since iron is less reactive as compared to zinc and magnesium, it too will plateau out on the same level, but initial reaction will be much slower
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Can some1 help me pls?
the question says that "A sample of orange fruit jam was investigated to check the three colourings preesnt.
Step 1 = the jam was boiled with water"
the question asks the purpose of step 1?
could u please explain me clearly the purpose of it?
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With magnesium pieces initial rate of reaction will be much lower, but it will plateau out on the same(over a longer period of time)
With iron powder, it will be still lower, since iron is less reactive as compared to zinc and magnesium, it too will plateau out on the same level, but initial reaction will be much slower
oh thanks ! thats exactly what i wanted to kno about the ( PLATEAU ) bit
and thanks for the slap thingy :P
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haha..not a problem mate
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Can some1 help me pls?
the question says that "A sample of orange fruit jam was investigated to check the three colourings preesnt.
Step 1 = the jam was boiled with water"
the question asks the purpose of step 1?
could u please explain me clearly the purpose of it?
LOL this is may june 2006!>im doin the same past paper right now
well i wrote to dissolve the colours..
mark scheme says to EXTRACT THE COLOURS... Boil it and it dissolves :/ cant explain more than that
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_6.pdf
can some1 help me with qeustion 4?
the graphs? can some1 draw them ?
its been really difficult for me .. the software (paint =P) doesnt allow me to curve the line more than twice .. there are some points tht dont come on the curve .. actually they wont come even on a hard copy
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its been really difficult for me .. the software (paint =P) doesnt allow me to curve the line more than twice .. there are some points tht dont come on the curve .. actually they wont come even on a hard copy
ouch :P
lol thanks :P i got what i wanted from nid :P sorry for wasting your time :-X :-\
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I already revised the lab apparatus and the experiements. The only thing i don't know are the tests, does anyone know which chapter they are or better yet what is the chapter which needs to be the most focused one for tests? Also thanks, and good luck.
Don't worry people, its just P6 and its only for 20% so yeah.
If u want the tests .. on the last page
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ouch :P
lol thanks :P i got what i wanted from nid :P sorry for wasting your time :-X :-\
i saw ur PM .. AFTER posting .. its ok .. ;)
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If u want the tests .. on the last page
Thanks! And good luck for tomorrow dude, and also especially paper 4 maths. I hope we all do good since i messed up big time in paper 2 but oh well, what ever happened, happened.
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LOL this is may june 2006!>im doin the same past paper right now
well i wrote to dissolve the colours..
mark scheme says to EXTRACT THE COLOURS... Boil it and it dissolves :/ cant explain more than that
Thank you Kimo :)
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https://studentforums.biz/index.php/topic,7663.0.html
something i made for the paper 6 2mrw
goodluck ! ;D
Thanks!
Goodluckk! =)
By the way do we need to revise organic chemistry for Paper 6? Apart from proving that a substance is an unsaturated hydrocarbon (using bromine water), is there anything else?
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Thanks!
Goodluckk! =)
By the way do we need to revise organic chemistry for Paper 6? Apart from proving that a substance is an unsaturated hydrocarbon (using bromine water), is there anything else?
alcohols flammable...colourless...fuel smell..thats it i guess
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hey guys i want to noe wat is titration i m really confused ??????????????
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alcohols flammable...colourless...fuel smell..thats it i guess
By the way there was this question - They want to find out whether ethanol or methanol provides more heat energy when burnt.
In that case do you use a metal caloriemeter and a spirit burner?
Heat a known volume of water with a spirit burner which burns ethanol. Note the temperature change and then repeat with methanol and compare the temperature change of the water. Is that what you're supposed to do?
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have no idea whats a colri meter
anyway what you do
Measure the itial volume of spirit burner wiht ethanol
pur 100cm3 of distillled water in a copper can by a measureing cyylinder
then Heat to a certain temperature eg 30* C
then measure the final mass of spirit burner
Repeat with other alcohol! and compare the masses!
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m/j 2007 qeustion 4
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_qp_6.pdf
whats goin on ? i dunno how to asnwr (a)
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used as an indicator .. to check the presence of iodine .. solved this one yest ;)
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used as an indicator .. to check the presence of iodine .. solved this one yest ;)
yea but why check if iodine is present ?
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m/j 2007 qeustion 4
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_qp_6.pdf
whats goin on ? i dunno how to asnwr (a)
Same ppr q 5 (d) ???never heard of such a thin in ma whole life ?? can some one ans this:)
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Guys where can i find past papers before 2001 ... theyre not on this website .. i just wanted to look at them to check how they are and stuff
IM talking about chemistry paper 6
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Same ppr q 5 (d) ???never heard of such a thin in ma whole life ?? can some one ans this:)
its an iodine test
SOLID C IS LEAD CARBONA + HNO3 and theres potassium iodide
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Guys where can i find past papers before 2001 ... theyre not on this website .. i just wanted to look at them to check how they are and stuff
IM talking about chemistry paper 6
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/1993-2003/ChemistryExamP61993-2003.pdf
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That includes paper 6 ?
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help me wid this Q plz!!! :S
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its an iodine test
SOLID C IS LEAD CARBONA + HNO3 and theres potassium iodide
Thanks but i thought test for iodine is add nitric acid then add lead(II)nitrate....yellow ppt.
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help me wid this Q plz!!! :S
the 30 c one i think caz it should fall constantly:D 40 on x and 30 on y:D
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help me wid this Q plz!!! :S
which paper is it By the way
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which paper is it By the way
June 2009 .. 06! ..... i wanted to know ..where to draw the lines ?.?
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yea but why check if iodine is present ?
dunno i wrote because "Starch" always follows "Iodine" .. =P .. i think to check whether all the iodine is reacted in the reaction .. because for this reaction Iodine ions are formed before .. it is not a direct reaction .. my sir told me .. we dont hav to learn the details .. trust me its very complicated .. (my sir also loves to show off his chemi ) :P :P
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Thanks but i thought test for iodine is add nitric acid then add lead(II)nitrate....yellow ppt.
remember anything that involves Lead and Iodine is always "yellow ppt." .. read the main question u'll get me ..
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June 2009 .. 06! ..... i wanted to know ..where to draw the lines ?.?
here u go:D
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help me wid this Q plz!!! :S
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Hey, for the electrolysis questions, these question are repeated frequently > What observations woud yu see when the switch is closed?
And > Precautions to make the expirement safe?
Thanks in advance :)
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What do you do with the prediction temperature questions and the difference?
Thanks!
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here u go:D
u forgot to attach it right ?? =P happens ..
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dunno i wrote because "Starch" always follows "Iodine" .. =P .. i think to check whether all the iodine is reacted in the reaction .. because for this reaction Iodine ions are formed before .. it is not a direct reaction .. my sir told me .. we dont hav to learn the details .. trust me its very complicated .. (my sir also loves to show off his chemi ) :P :P
i see thanks :D
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?n exothermic reactions, the temperature in the beaker should decrease, since it is giving out some heat, but in the mark scheme it says that temp increases. im really confused. can u pls help ? :(
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Hey, for the electrolysis questions, these question are repeated frequently > What observations woud yu see when the switch is closed?
And > Precautions to make the expirement safe?
Thanks in advance :)
if a bulb is present .. bulb lights .. or state the decomposition of the electrolyte for eg ..
electrolysis of molten Leadbromide
at cathode
tiny silver beads (Pb)
at anode
orange/brown gas (Br)
safer : wear gloves, lab glasses, lab coat
well ventilated room or fume cupboard
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What do you do with the prediction temperature questions and the difference?
Thanks!
see of the volume of the solution doubled .. temp halved
volume of solution halved .. temp doubled
post any particular paper u'll understand better
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?n exothermic reactions, the temperature in the beaker should decrease, since it is giving out some heat, but in the mark scheme it says that temp increases. im really confused. can u pls help ? :(
exothermic reactions "give out" heat .. remember exo- outside
endothermic reactios "use up" heat .. remember endo - inside
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exothermic reactions "give out" heat .. remember exo- outside
endothermic reactios "use up" heat .. remember endo - inside
as u said it gives out heat, so the temp in the beaker where the exhothermic rxn takes place should decrease right?
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u forgot to attach it right ?? =P happens ..
:P yes :P
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as u said it gives out heat, so the temp in the beaker where the exhothermic rxn takes place should decrease right?
the temp in the beaker will increase
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the temp in the beaker will increase
hmm. ok when I thought deeply, i realesed that it should increase. Thanks.
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as u said it gives out heat, so the temp in the beaker where the exhothermic rxn takes place should decrease right?
whoa whoa clear ur concepts =S .. i'll try to think something practical for u .. try this .. pour some hot water in a drinking glass imagine the hot water is a result of an exothermic reaction .. what do u feel when u touch the glass ??
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hey can any1 help me wid hw 2 demonstrate the solvent extraction of chorophyll 8)
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whoa whoa clear ur concepts =S .. i'll try to think something practical for u .. try this .. pour some hot water in a drinking glass imagine the hot water is a result of an exothermic reaction .. what do u feel when u touch the glass ??
of course it will be hot. yes it clear enough for now. thx in advice. :)
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drop leaf in boiling water for some time.
take it out and put it in a test tube full of alcohol(in a water bath.
take the leaf out( green colour should be there in the alcohol.
than heat the alcohol in the water bath till only green powder remains.
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n wat it its for dyes like jams n fruits
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drop leaf in boiling water for some time.
take it out and put it in a test tube full of alcohol(in a water bath.
take the leaf out( green colour should be there in the alcohol.
than heat the alcohol in the water bath till only green powder remains.
n so if they ask y step 1 is done
the answer is to extract leaf color
m i ryt!!!!!
:?
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hw 2 prevent leakage of power 4rom over head pipes
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drop leaf in boiling water for some time.
take it out and put it in a test tube full of alcohol(in a water bath.
take the leaf out( green colour should be there in the alcohol.
than heat the alcohol in the water bath till only green powder remains.
but my teacher told me grind the plant materail in a small amount of water and put into a seperating funnel and add petroleum ther (i was wonderin y ) and shake
chorophyll is extracted into the solvent layer
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Oct/nov 2003 Paper 6 chemistry question 5 part D "suggest why conc.sulphuric acid should not be used to dry ammonia" and also in the E part I checked mark scheme answer its says that the mistake correction is "tubes should be evened", explanation " liquid would be transfered to gas jar" can someone explain this to me I didnt understand what liquid theyre talking about.
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n so if they ask y step 1 is done
the answer is to extract leaf color
m i ryt!!!!!
:?
but we need 2 extract chorophyll n this in chem nt bio :)
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Oct/nov 2003 Paper 6 chemistry question 5 part D "suggest why conc.sulphuric acid should not be used to dry ammonia" and also in the E part I checked mark scheme answer its says that the mistake correction is "tubes should be evened", explanation " liquid would be transfered to gas jar" can someone explain this to me I didnt understand what liquid theyre talking about.
this is becuz de conc. SO4 vil react with ammonia rather den dryin it
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Looking through past papers, I noticed there are a lot of questions involving justifications, reasoning and stuff like variables in an experiment etc. that are repeated between years.
Well it's more like the Physics paper 6 where we usually get questions involving justifications, and looking at this topic: https://studentforums.biz/index.php/topic,7496.0.html, it really helped me a lot in solving PP and my real exam, so if there's anyone who can summarize all of those repeated questions that way for chemistry, I'm sure a lot of us here would really find it useful and appreciate it before our exam tomorrow...
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but we need 2 extract chorophyll n this in chem nt bio :)
i noe chem i dnt tak bio evn
i think it shud be crushed n den ..................<i dnt noe den wat>
bt ya i thnk leaf or flowers are supposed 2 be crushed n den do sumthin
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Anyone knows a site that explains the three methods of gas delivery?
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Looking through past papers, I noticed there are a lot of questions involving justifications, reasoning and stuff like variables in an experiment etc. that are repeated between years.
Well it's more like the Physics paper 6 where we usually get questions involving justifications, and looking at this topic: https://studentforums.biz/index.php/topic,7496.0.html, it really helped me a lot in solving PP and my real exam, so if there's anyone who can summarize all of those repeated questions that way for chemistry, I'm sure a lot of us here would really find it useful and appreciate it before our exam tomorrow...
Yes its so true, I hope someone can make a guide for P6 chemistry like that one for physics...and really fast! :-\
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Anyone knows a site that explains the three methods of gas delivery?
u mn the upward delivery thingy
reply fast mayb i cn help
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Yes its so true, I hope someone can make a guide for P6 chemistry like that one for physics...and really fast! :-\
https://studentforums.biz/index.php/topic,7663.0.html
i made this..
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Anyone knows a site that explains the three methods of gas delivery?
well i dont know a site but ill tell ya wat they are
UPWARD DELIVERY-FOR GASES LESS DENSE THAN AIR'
DOWNWARD DELIVERY-FOR GASES DENSER THAN AIR
GAS SYRINGE-TO FIND VOLUME OF GAS
COLLECTION OVER WATER-FOR GASES THAT ARE NOT SOLUBLE IN WATER
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what is barium chloride used to test for??
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Yes, I saw it and thanks for that but if you saw the link I posted, it's more like the repeated answers for questions which are usually at the end of the experiments.
Eg. What type of reaction is shown?
Give possible errors in this experiment.
Why was the rate of reaction in A more than that in B?
etc.
In other words, the stuff that usually always come including tests for pure water, Alkenes etc.
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u mn the upward delivery thingy
reply fast mayb i cn help
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what is barium chloride used to test for??
+ dilute nitric acid
test for sulfate ions
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u mn the upward delivery thingy
reply fast mayb i cn help
yayayayaaya.... was that fast enough xD
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well i dont know a site but ill tell ya wat they are
UPWARD DELIVERY-FOR GASES LESS DENSE THAN AIR'
DOWNWARD DELIVERY-FOR GASES DENSER THAN AIR
GAS SYRINGE-TO FIND VOLUME OF GAS
COLLECTION OVER WATER-FOR GASES THAT ARE NOT SOLUBLE IN WATER
Thx but i wanted to see pics, cuz i wanna see how the water level is...
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Hey guys im thinking about Moles/concentration,etc , do we have to learn all the formulas for concentration of water,air,etc if yes then im screwed because I dont know anything about them neither the time to learn them (thank god P3 got 10 days between) and if yes and im screwed can someone tell me what questions are there in any p6? :'(
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Hey guys im thinking about Moles/concentration,etc , do we have to learn all the formulas for concentration of water,air,etc if yes then im screwed because I dont know anything about them neither the time to learn them (thank god P3 got 10 days between) and if yes and im screwed can someone tell me what questions are there in any p6? :'(
THERE ARE NO QUESTIONS RELATING TO MOLES IN PAPER 6.
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Thx but i wanted to see pics, cuz i wanna see how the water level is...
its takin a lot of tym 2 post pictures
u cn chk out images on google
:))))))
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Thx but i wanted to see pics, cuz i wanna see how the water level is...
well i have a wksht wid some pics but they arent that clear
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Its okay, thx anyway i just wanted to check, nothing big :P
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THERE ARE NO QUESTIONS RELATING TO MOLES IN PAPER 6.
*phew* what a relief, I was sweating buckets! ;D
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hey can any1 help me wid hw 2 demonstrate the solvent extraction of chorophyll 8)
hey sorry my nets working realy bad .. sorry cannot demonstrate right now .. solve oct/nov 20009 paper 6 last question ..
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Yes, I saw it and thanks for that but if you saw the link I posted, it's more like the repeated answers for questions which are usually at the end of the experiments.
Eg. What type of reaction is shown?
Give possible errors in this experiment.
Why was the rate of reaction in A more than that in B?
etc.
In other words, the stuff that usually always come including tests for pure water, Alkenes etc.
k jus a suggestion :
on a new page evry1 jus share questions which repitively cum wid answers
dnt repeat questions
if u agree i will create the topic n lts start
it will b gud revisn <i thnk sooo>
:>>>>
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http://www.google.com.bh/imgres?imgurl=http://scienceaid.co.uk/chemistry/applied/images/delivery.png&imgrefurl=http://scienceaid.co.uk/chemistry/applied/gases.html&usg=__ztNR-hT0nsB4mFDvLhNfBv6QaDA=&h=291&w=381&sz=20&hl=en&start=4&itbs=1&tbnid=4WuPj3Hwzt3QyM:&tbnh=94&tbnw=123&prev=/images%3Fq%3Ddownward%2Bdelivery%26hl%3Den%26sa%3DX%26gbv%3D2%26tbs%3Disch:1 (http://www.google.com.bh/imgres?imgurl=http://scienceaid.co.uk/chemistry/applied/images/delivery.png&imgrefurl=http://scienceaid.co.uk/chemistry/applied/gases.html&usg=__ztNR-hT0nsB4mFDvLhNfBv6QaDA=&h=291&w=381&sz=20&hl=en&start=4&itbs=1&tbnid=4WuPj3Hwzt3QyM:&tbnh=94&tbnw=123&prev=/images%3Fq%3Ddownward%2Bdelivery%26hl%3Den%26sa%3DX%26gbv%3D2%26tbs%3Disch:1)
WOW xD
Found this for delivery if anyone wants... just go down, don't press on the pic...
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Its okay, thx anyway i just wanted to check, nothing big :P
no prob
ill still upload the pics in a few
it might help sum 1 else
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Thx but i wanted to see pics, cuz i wanna see how the water level is...
here you gooooo
=DDD
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http://www.google.com.bh/imgres?imgurl=http://scienceaid.co.uk/chemistry/applied/images/delivery.png&imgrefurl=http://scienceaid.co.uk/chemistry/applied/gases.html&usg=__ztNR-hT0nsB4mFDvLhNfBv6QaDA=&h=291&w=381&sz=20&hl=en&start=4&itbs=1&tbnid=4WuPj3Hwzt3QyM:&tbnh=94&tbnw=123&prev=/images%3Fq%3Ddownward%2Bdelivery%26hl%3Den%26sa%3DX%26gbv%3D2%26tbs%3Disch:1 (http://www.google.com.bh/imgres?imgurl=http://scienceaid.co.uk/chemistry/applied/images/delivery.png&imgrefurl=http://scienceaid.co.uk/chemistry/applied/gases.html&usg=__ztNR-hT0nsB4mFDvLhNfBv6QaDA=&h=291&w=381&sz=20&hl=en&start=4&itbs=1&tbnid=4WuPj3Hwzt3QyM:&tbnh=94&tbnw=123&prev=/images%3Fq%3Ddownward%2Bdelivery%26hl%3Den%26sa%3DX%26gbv%3D2%26tbs%3Disch:1)
WOW xD
Found this for delivery if anyone wants... just go down, don't press on the pic...
lol dint hlp me wid delivery tube thingy
bt nyc site :P
-
HERE YA GO
IT ALSO HAS HOW TO DRY GASES
-
k jus a suggestion :
on a new page evry1 jus share questions which repitively cum wid answers
dnt repeat questions
if u agree i will create the topic n lts start
it will b gud revisn <i thnk sooo>
:>>>>
Well, I'm sure I don't mind, besides it will be helpful for everyone, as long as it's in proper English so I'd be able to at least understand what you're trying to say.
-
omg i said its okay xD
U guys are really helpful thx ;) :D
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HERE YA GO
IT ALSO HAS HOW TO DRY GASES
Ya i needed that too :D
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Ya i needed that too :D
glad i uploaded it then
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Please someone post me a link to the mark scheme of may/june 2000 P6 chemistry!
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Well, I'm sure I don't mind, besides it will be helpful for everyone, as long as it's in proper English so I'd be able to at least understand what you're trying to say.
ok start here
https://studentforums.biz/index.php/topic,7836.0.html
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Please someone post me a link to the mark scheme of may/june 2000 P6 chemistry!
https://studentforums.biz/index.php/topic,54.945.html
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HERE YA GO
IT ALSO HAS HOW TO DRY GASES
how to dry gas was really hlp ful
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how to dry gas was really hlp ful
no prob glad i cud help
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FUNNY GOAL: I WILL FINISH ALL THE P6 OF CEM AGIAN AND ALSO FOR BIOLOGY P6 JUST PRAY THTS IT
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no prob glad i cud help
indeed .. thanks .. +rep
i only knew sulfuric acid .. =)
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no prob anytime
-
no prob anytime
so r u done with chemi ??
wat all did u study ?
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umm well i did my chem board last year
well i studied all the apparatus and all the methods of collecting and drying
alss all dat titration precipitation and formation of salts
the anion and cation test
and i don't remembe
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umm well i did my chem board last year
well i studied all the apparatus and all the methods of collecting and drying
alss all dat titration precipitation and formation of salts
the anion and cation test
and i don't remembe
Oh im sorry .. i did hav a faint idea u werent doin igs this year .. Thanks
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lol its okay
dont worry ull do fine
dont panic relax get a good nights sleep and go into the examination hall feelin confident and ur hard work will pay off
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test to distinguish btwn zinc carbonate and zinc chloride
i wrote test: add HCl
zinc carbonate : effervescence of CO2 which turns lime watr milky
zinc chloride no reaction
is it crrct
:P
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Sure, we'll go all confident.
That is, ONCE WE'VE STARTED STUDYING! :P
Man, preparation so far sucks. :(
You Vin, what've you done?
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test to distinguish btwn zinc carbonate and zinc chloride
i wrote test: add HCl
zinc carbonate : effervescence of CO2 which turns lime watr milky
zinc chloride no reaction
is it crrct
:P
Yes, correct. :)
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dont ask .. 16 hrs of day passed and jus solved 3 papers .. =\
wbu?
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dont ask .. 16 hrs of day passed and jus solved 3 papers .. =\
wbu?
Man, we solved all the papers from 2000-2009 in school, and I filled all my booklet.
That was like a few months back.
Now I feel I don't remember anything.
And since the booklet is checked and marked, I can't even solve the papers myself again, so can't check if I know anything.
I don't know what to do. :S
I should revise all the tests once again, and look through the pp.
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Man, we solved all the papers from 2000-2009 in school, and I filled all my booklet.
That was like a few months back.
Now I feel I don't remember anything.
And since the booklet is checked and marked, I can't even solve the papers myself again, so can't check if I know anything.
I don't know what to do. :S
I should revise all the tests once again, and look through the pp.
dats so kool u guys actually did dat
LUCKY !!!! ;)
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Shazizzle ur lucky, my school didn't even finish one paper with us NOT ONE!!!
Anyway, enough with the stupid school :P
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_6.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_6.pdf)
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_ms_6.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_ms_6.pdf)
Q)3)c)ii) Can someone 'translate' what the mark scheme says :P
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Yes, correct. :)
n ya Thanks
=D
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Hey any paper tht u found REAL hard .. i'll solve those ones first .. Thanks
-
y do we need to dry a gas??
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+ dilute nitric acid
test for sulfate ions
and do we get white ppt?
-
yup
u get a white ppt
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Shazizzle ur lucky, my school didn't even finish one paper with us NOT ONE!!!
Anyway, enough with the stupid school :P
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_6.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_6.pdf)
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_ms_6.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_ms_6.pdf)
Q)3)c)ii) Can someone 'translate' what the mark scheme says :P
they simply mean that it might contain some impurity ..
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O ya :P Thanks. Lets just hope they start speaking normal english...
Hey sorry :P Same paper ;D Hmm.. 4)b)iii) it says Hydrogen... where did it come from ?? Is it cuz its AQUEOUS Copper Sulphate?
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Yeah, we start IGCSE in grade 8, so we get a whole extra year, grade 10, to solve papers and clear doubts. Cool innit? :P
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O ya :P Thanks. Lets just hope they start speaking normal english...
Hey sorry :P Same paper ;D Hmm.. 4)b)iii) it says Hydrogen... where did it come from ?? Is it cuz its AQUEOUS Copper Sulphate?
Umm, the observations say 'lighted splint pops', so that's just the test for hydrogen, proving its presence.
You don't need to know why, but , yes, I believe because of the aqueous. :P It's water, so contains H+ and OH- ions.
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Yeah, we start IGCSE in grade 8, so we get a whole extra year, grade 10, to solve papers and clear doubts. Cool innit? :P
OMG 0.0 Its cool ya but no offense kinda stupid ;) Its just wrong to spend all that time studying the same stuff... One of the things i hate about IGCSE, is that they make u do it their way. (u have to know how to answer, solve questions, same style) Like u might know the right answer, but they still give it wrong cuz u didnt write it right way.. WTF 0.o thats just gay. The only good thing about it is that we dont memorize, we understand (to a certain extent xD)
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Umm, the observations say 'lighted splint pops', so that's just the test for hydrogen, proving its presence.
You don't need to know why, but , yes, I believe because of the aqueous. :P It's water, so contains H+ and OH- ions.
thx ;)
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Okay guys, correct me if I'm wrong, and if you can find and accurate source of these, please share.
-All Chlorides, bromides and iodides are soluble except lead chloride/bromide/iodide, silver Cl/Br/I, and mercury Cl/Br/I
-All sulphates are soluble except lead sulphate, barium sulphate and calcium sulphate
-All carbonates are insoluble except Sodium, potassuim and ammonium carbonates, which are soluble.
-All hydroxides are insoluble except Sodium, potassium and ammonium hydroxides, which are soluble.
-All nitrates are soluble
Thanks :)
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Correct. Tho i don't know Hydroxides and some of the first line i also dont know :P
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This is wat my book says. Cross check it. :)
Insoluble compounds.
Chlorides, bromides, iodides of silver and lead.
Sulfates of Calcium, barium and lead.
All hydroxides except those of group 1
All carbonates except those of group 1
Metal oxides except group 1 and 2s.
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yup ;) ;)
add sodium with potassium .. i guess thts understood
All sulphides and sulphites are insoluble except potassium , sodium , ammonium
All OXIDES are insoluble except calcium, potassium and ammonium ,
Ca(OH)2 is partially soluble right .. jus wanna make sure .. ;) ;)
NOTE :
PbCl2 is soluble in hot water
AgCl is soluble in aq. ammonia
-
Acids - Donate Proton (H+)
Bases - Accept Proton (H+)
Alkalis - soluble bases
Basicity - No of replaceable hydrogen ions
Monobasic - 1 replaceable H+ e.g HCl
DiBasic - 2 replaceable H+ e.g H2SO4
Strong acids/alkalis - fully dissociate/ionise - HCl & NaOH
Weak acids/alkalis - only partially dissociate/ionise - CH3COOH & NH4OH
Indicators
Red Litmus paper - Red in acidic - blue in alkaline
Blue Litmus paper - Red in acidic - blue in alkaline
methyl orange - orange/pink in acidic - yellow in alkaline
methyl red - red in acidic - yellow in alkaline
Phenolphthalein - colourless in acidic - pink in alkaline
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sh*t MAN. I need that xD :D Thankss :P
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yup ;) ;)
add sodium with potassium .. i guess thts understood
All sulphides and sulphites are insoluble except potassium , sodium , ammonium
All OXIDES are insoluble except calcium, potassium and ammonium ,
Ca(OH)2 is partially soluble right .. jus wanna make sure .. ;) ;)
NOTE :
PbCl2 is soluble in hot water
AgCl is soluble in aq. ammonia
Yup. The study guide says, ALL HYDROXIDES ARE INSOLUBLE EXCEPT GROUP 1 METALS (SODIUM, POTASSIUM ETC), CALCIUM, STRONTIUM AND BARIUM.
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/1993-2003/chemistry1993-2000answers.pdf
In this one at may/june 2000 answer 6 b what does O.I.M mean?
"fill the burette with O.I.M hydrochloric acid solution"
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m/j 2009 ques 4 e) 1)
????????????
n 1 more thing for the sam ques
the ms says dat "extrapolation shown"
wat do u mn by extrapolation shown
THNXXX
:)
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m/j 2009 ques 4 e) 1)
????????????
n 1 more thing for the sam ques
the ms says dat "extrapolation shown"
wat do u mn by extrapolation shown
THNXXX
:)
Extrapolation means you extend the curve forward, roughly till 70 deg. C, i.e extend it in the same direction roughly till it touches the end f the grid.
You use the approximate estimated result you get, using the graph, by showing your working lines. :)
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m/j 2009 ques 4 e) 1)
????????????
n 1 more thing for the sam ques
the ms says dat "extrapolation shown"
wat do u mn by extrapolation shown
THNXXX
:)
Shaizzzzle answered it? u want the whole q to be answered??
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Shaizzzzle answered it? u want the whole q to be answered??
yup thnku
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Shaizzzzle answered it? u want the whole q to be answered??
Just three 'z's will do. :P No need for the fourth ;)
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a) Just read the temperature from the thermometer and write it in the box. Easy 'nuff. FOr the average add the initial and final and divide the sum by 2.
b) Use the last 2 columns from the table to plot the curve. Remember it should be a smooth curve.
ci) Experiment 5
cii) As the temperature is highest, the particles will have more energy and thus will move faster to increase the number of collisions.
d) To obtain fair result by keeping the variables constant.
e)i) Shaizzzle answered it.
eii) New curve should be lower than the original curve as more concentration will reduce the time for printed text to disappear.
@Shaizzzle - LOL, K, :P
f) Use insulation
Reduce Heat loss.
-
m/j 2009 ques 4 f
the mark scheme says use of data logger/colourimeter
wats dat ????
Thanks
-
for bar graphhs
DO WE LEAVE 1 SPACE B4 THE FIRST AND 1 BETWEEN EACH 1?
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a) Just read the temperature from the thermometer and write it in the box. Easy 'nuff. FOr the average add the initial and final and divide the sum by 2.
b) Use the last 2 columns from the table to plot the curve. Remember it should be a smooth curve.
ci) Experiment 5
cii) As the temperature is highest, the particles will have more energy and thus will move faster to increase the number of collisions.
d) To obtain fair result by keeping the variables constant.
e)i) Shaizzzle answered it.
eii) New curve should be lower than the original curve as more concentration will reduce the time for printed text to disappear.
@Shaizzzle - LOL, K, :P
f) Use insulation
Reduce Heat loss.
m ssoooo sorrryyyyy 2 waste ur tym :-\
actually i jus wantd que 4 e 1 and 2
sOOORRRRRYYYY 1ce agn
n Thanks
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for bar graphhs
DO WE LEAVE 1 SPACE B4 THE FIRST AND 1 BETWEEN EACH 1?
btwen each 1 u have 2 leave
dunno abtt b4 the first 1
which yr did u fynd this ques
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btwen each 1 u have 2 leave
dunno abtt b4 the first 1
which yr did u fynd this ques
not sure ..a freinds question...
I NEED TO KNO DO WE LEAVE A SPACE B4 THE FIRST BAR IN A BAR GRAPH
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for bar graphhs
DO WE LEAVE 1 SPACE B4 THE FIRST AND 1 BETWEEN EACH 1?
Umm, yes the bars have to be separate.
But it depends on the number of boxes given on the x axis.
If, for example you have to plot 5 experiments, and they give you 5 big boxes, then leave blank, one small box from either side of the bar, even the first, so you are infact using the middle 8 small boxes for each bar. :)
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Umm, yes the bars have to be separate.
But it depends on the number of boxes given on the x axis.
If, for example you have to plot 5 experiments, and they give you 5 big boxes, then leave blank, one small box from either side of the bar, even the first, so you are infact using the middle 8 small boxes for each bar. :)
ok cheers thank you
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used as an indicator .. to check the presence of iodine .. solved this one yest ;)
its used as an indicator...to check presence of starch!!..not iodine...
...... :P
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its used as an indicator...to check presence of starch!!..not iodine...
...... :P
check it urself .. chem not bio ..
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_ms_6.pdf
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_qp_6.pdf
Q 4 a. its a diff ques.
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its used as an indicator...to check presence of starch!!..not iodine...
...... :P
i mean i jus wanted to know tht do u mean tht we r checkin IOdine 's presence by starch????
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/1993-2003/chemistry1993-2000answers.pdf
In this one at may/june 2000 answer 6 b what does O.I.M mean?
"fill the burette with O.I.M hydrochloric acid solution"
u will only be marked if uy include hcl in ur ans....i think so:p
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i mean i jus wanted to know tht do u mean tht we r checkin IOdine 's presence by starch????
lol hamz u startd past pprs
:P
By the way <konsa ppr kr rahi ho? jaLdi bata>
-
So, when something 'smells of vinegar', it's an organic salt? :S
Also, when condensation forms on the top of the tube, it's a hydrated salt? :S
And because it 'smells like petrol', it's an alkane/organic hydrocarbon? :S
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i mean i jus wanted to know tht do u mean tht we r checkin IOdine 's presence by starch????
wht not ?? not specifically but u hav a look at the paper .. it has to mean that way .. if u can check the presence of starch by iodine .. why cant u do that the other way .. ultimately u get blue/black colouration ..
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So, when something 'smells of vinegar', it's an organic salt? :S
Also, when condensation forms on the top of the tube, it's a hydrated salt? :S
And because it 'smells like petrol', it's an alkane/organic hydrocarbon? :S
aaa wat is a hydrated salt:S
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Sab chup beth ke past papers karo. :P
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aaa wat is a hydrated salt:S
One with water.
i.e opposite to anhydrous.
Blue Copper (II) Sulphate crystals are hydrated. The white anhydrous salt has no water.
-
Sab chup beth ke past papers karo. :P
jaise tum kahoo =P
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guys dont panic BUT THE EXAM IS TOMORROW :o :o :o time flies
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So, when something 'smells of vinegar', it's an organic salt? :S
Also, when condensation forms on the top of the tube, it's a hydrated salt? :S
And because it 'smells like petrol', it's an alkane/organic hydrocarbon? :S
very trueeeeeeeeeeeeeeeeeeeee
alcohol not alkane but yea the 5th alkane on words are liquids so ye a maybe i think soo ! can u check again on teh mark scheme?
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i.e it loses its 'water of crystallisation'.
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aaa wat is a hydrated salt:S
SOME salts can be hydrated. This means they fit water molecules in them. The formula is like this: CuSO4.5H20......... MgSO4.7H20..... CoCl2.6H20
If you heat these they will lose their water molecule and become anhydrated.
This is why they are used in testing of water. If solution has water, they will turn blue. If u add the solution and it doesnt have water, then they will stay white
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lol hamz u startd past pprs
:P
By the way <konsa ppr kr rahi ho? jaLdi bata>
bhaaag kyun gaye!!!!! k call me wen u cum onlin agn
me goin 2 hav some sleep< SHAYED lol>
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k guyz 1 more ques tests with barium chloride <i dunnoo>
lik example :To the third portion of the blue solution,(which is copper (11))
dilute hydrochloric acid was added
followed by barium chloride
solution.
tel answer
n tel if there r ny othr tests wid barium chloride :)))
Thanks
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k guyz 1 more ques tests with barium chloride <i dunnoo>
lik example :To the third portion of the blue solution,(which is copper (11))
dilute hydrochloric acid was added
followed by barium chloride
solution.
tel answer
n tel if there r ny othr tests wid barium chloride :)))
Thanks
it is frm ppr m/j 2009 By the way
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k guyz 1 more ques tests with barium chloride <i dunnoo>
lik example :To the third portion of the blue solution,(which is copper (11))
dilute hydrochloric acid was added
followed by barium chloride
solution.
tel answer
n tel if there r ny othr tests wid barium chloride :)))
Thanks
barium chloride ests for sulPHAte man the key for SULPHATE IS BARIUM because it react and give barium sulphate which is insoluble whit ppt got it? ???6394
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it is frm ppr m/j 2009 By the way
This is to test the presence of sulphate ions.
The answer to this is White Precipitate forms.
As it is Copper (II) Sulphate, it forms Barium Sulphate (an insoluble salt) on reacting with barium chloride, proving presence of Sulphate.
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barium chloride ests for sulPHAte man the key for SULPHATE IS BARIUM because it react and give barium sulphate which is insoluble whit ppt got it? ???6394
oh yaaaaaaaaaaaaaaaaaaaaaaaa
ooops i totally 4 get dat
Thanks both of u
:P :P
-
rofl =D
now i wont 4 get this bcoz of wat jus hppnd
lol
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ok do i have future in teaching XD lol
-
lol
u r nt bad at it
thou attention :U WILL BE FUNNY TEACHER !!!<funny as in a gud way>
:P
-
thx 2rf3lk l qb3a XD
-
thx 2rf3lk l qb3a XD
=D
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@ DEGO
i noe u myt be tyred of this ques bt....... :P
so r u done for phy?????????????? n hw well r u prepard
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physics well ;D actually i am meaning to take it next june :-\ but i guess people said it's exams are easy this year
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physics well ;D actually i am meaning to take it next june :-\ but i guess people said it's exams are easy this year
so u mn u r nt givin ur igs ryt nw
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so u mn u r nt givin ur igs ryt nw
XD i dn know wtcha mean !
-
can somebody give me a list of apparatus that we should know?
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can somebody give me a list of apparatus that we should know?
lol i was about to post same request need the lab tools we should know pls if any one hv notes for these i wnt to revise it and check spelling of these tools 2MORROW ISNT SO FAR :'(
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i'll check for it .. i'd posted it earlier .. now im working on my laptop i dont hav it the hard disk ..
here ..
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lol i was about to post same request need the lab tools we should know pls if any one hv notes for these i wnt to revise it and check spelling of these tools 2MORROW ISNT SO FAR :'(
chk ot this
http://cantonhighchem.com/files/lab%20equipment%20sheet%20side%20a.jpg<ignore some>
or else w8 for nyt i will upload thm soon
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chk ot this
http://cantonhighchem.com/files/lab%20equipment%20sheet%20side%20a.jpg<ignore some>
or else w8 for nyt i will upload thm soon
k i ll wait cn u just pm me whn u upload thm XD Thank You
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nice!!!
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k i ll wait cn u just pm me whn u upload thm XD Thank You
ya sure
do u evn want nts cos we jus need to noe the apparatus n i hve nts 4 a few imp. apparatus lik measurin cylinder/pipette,mortar n pestle
actually u dnt need notes
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hey wat about p6 biology i need notes including all the possible experiments plz
thanx (i hope today0
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is preparation of salts as important as identification of ions?
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thx everybody for the apparatus notes....
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is preparation of salts as important as identification of ions?
they are both very important..but idntifyin is always on evry past paper for atleast 15-20 marks
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^^^Yes, they're both equally important. There seems to be a lot of questions involving them in almost all past papers.
Their tests and results are EXTREMELY important. In fact most of Paper 6 is all about that section.
-
chem oct/nov 2006 p6 q 5b
pls
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Is organic chemistry important for paper 6?
-
chem oct/nov 2006 p6 q 5b
pls
Umm, in B(ii) and (iii), a (iii) and a (iv) are repeated, which are tests for the presence of chlorides, bromides or iodides.
Since in (b) the result for both is yellow, especially bright yellow with lead, it IS and iodide salt.
So, Potassium Iodide.
In B(i) it was added to distilled water as tests can only be applied when the salt is in solution, to show a result.
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^^I don't think so, I mean all you need from that part is the probably the tests for Alkenes and Alkanes etc. (And probably the fermentation and fractional distillation)
Question: When we say a substance is soluble, we mean that it dissolves well in water or all other solvents?
-
Is organic chemistry important for paper 6?
no
-
Is organic chemistry important for paper 6?
hey guys i wanted to noe are all neutralisation reactions exothermic.......if no then how do tell wat type of reaction it is????????
-
they always mention what it is soluble..for ex water-soluble ...or soluble in alcohol
but if they jsut say soluble..then for chromatography u say youse a sotuble solvent
and for analysis u say water ..i guess
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hey guys i wanted to noe are all neutralisation reactions exothermic.......if no then how do tell wat type of reaction it is????????
yes they are exothermic!
-
Yup. The study guide says, ALL HYDROXIDES ARE INSOLUBLE EXCEPT GROUP 1 METALS (SODIUM, POTASSIUM ETC), CALCIUM, STRONTIUM AND BARIUM.
Which study guide?
-
is preparation of salts as important as identification of ions?
oct/nov 2008 p6
qeustion 7 6 marks all about prep :O
-
Which study guide?
Question: When we say a substance is soluble, we mean that it dissolves well in water or all other solvents?
water i guess
-
water i guess
Any liquid solvent.
-
Which study guide?
The IGCSE Study Guide for Chemistry, Bob Berry, Hodder Education.
A more precise and to-the-point version of the original Hodder Education IGCSE Chemistry book, the Earl and Wilford one.
-
^I would have asked if there is an online ver. but it seems too good to be free, although I would have bought it or something, it's probably no use while my exam is tomorrow...Thanks anyways.
Also, can you list down all the solubles and insoluble again? This time a full list after all the corrections...
Another question, if hydrated means that it contains water then it is the same as when we say that a salt is in aqueous form right? Which means it's soluble.
So if this is right then Hydrated = Soluble/Aqueous form?
-
hey can any1 help me hw do we noe a substance is good dehydrating agent or hydrating agent hw can we prove it n can any1 list dem down :)
-
^I would have asked if there is an online ver. but it seems too good to be free, although I would have bought it or something, it's probably no use while my exam is tomorrow...Thanks anyways.
Also, can you list down all the solubles and insoluble again? This time a full list after all the corrections...
-All Chlorides, bromides and iodides are soluble except lead chloride/bromide/iodide, silver Cl/Br/I, and mercury Cl/Br/I
-All sulphates are soluble except lead sulphate, barium sulphate and calcium sulphate
-All carbonates are insoluble except Sodium, potassium (All group 1 metals in general) and ammonium carbonates, which are soluble.
-All hydroxides are insoluble except Sodium, potassium(All group 1 metals in general), ammonium, calcium, strontium and barium hydroxides, which are soluble.
-All nitrates are soluble
:)
-
^I would have asked if there is an online ver. but it seems too good to be free, although I would have bought it or something, it's probably no use while my exam is tomorrow...Thanks anyways.
Also, can you list down all the solubles and insoluble again? This time a full list after all the corrections...
Another question, if hydrated means that it contains water then it is the same as when we say that a salt is in aqueous form right? Which means it's soluble.
So if this is right then Hydrated = Soluble/Aqueous form?
hey can any1 help me hw do we noe a substance is good dehydrating agent or hydrating agent hw can we prove it n can any1 list dem down
-
hey can any1 help me hw do we noe a substance is good dehydrating agent or hydrating agent hw can we prove it n can any1 list dem down :)
hey can any1 plz help i realli in a state of big confusion :)
-
^I would have asked if there is an online ver. but it seems too good to be free, although I would have bought it or something, it's probably no use while my exam is tomorrow...Thanks anyways.
Also, can you list down all the solubles and insoluble again? This time a full list after all the corrections...
Another question, if hydrated means that it contains water then it is the same as when we say that a salt is in aqueous form right? Which means it's soluble.
So if this is right then Hydrated = Soluble/Aqueous form?
No, hydrated means it possesses water in its crystals. i.e Water of crystallisation.
Meaning, water was present inside the crystal granules.
Aqueous is when a salt is dissolved in water. i.e it is a solution.
Hydrated salts may not be soluble.
-
^I would have asked if there is an online ver. but it seems too good to be free, although I would have bought it or something, it's probably no use while my exam is tomorrow...Thanks anyways.
Also, can you list down all the solubles and insoluble again? This time a full list after all the corrections...
Another question, if hydrated means that it contains water then it is the same as when we say that a salt is in aqueous form right? Which means it's soluble.
So if this is right then Hydrated = Soluble/Aqueous form?
yes hydrated mean it is souble,and aqueous or crystalls
-
hey can any1 help me hw do we noe a substance is good dehydrating agent or hydrating agent hw can we prove it n can any1 list dem down :)
Never heard of anything called hydrating agent. Dehydrating agent removes water of crystallisation from a hydrated salt.
Eg : Sulfuric acid removes water of crystallisation from hydrated copper(II) sulfate
Also, Phosphorus pentoxide, obtained from the decomposition of aluminium phosphate is a dehydrating agent .
-
^I would have asked if there is an online ver. but it seems too good to be free, although I would have bought it or something, it's probably no use while my exam is tomorrow...Thanks anyways.
Also, can you list down all the solubles and insoluble again? This time a full list after all the corrections...
Another question, if hydrated means that it contains water then it is the same as when we say that a salt is in aqueous form right? Which means it's soluble.
So if this is right then Hydrated = Soluble/Aqueous form?
First, Hydrated salts contain "Water of Crystallization". A salt in aqueous form is when it is dissolved in water. CuSO4.5H2O is not the same as NaOH(aq)
Second, Soluble is not the same as Aqueous.
Soluble means the substance can be dissolved in any liquid solvent. Aqueous is when the solvent is water.
-
chem p6 2006 oct/nov q6b
Thanks
-
Never heard of anything called hydrating agent. Dehydrating agent removes water of crystallisation from a hydrated salt.
Eg : Sulfuric acid removes water of crystallisation from hydrated copper(II) sulfate
Also, Phosphorus pentoxide, obtained from the decomposition of aluminium phosphate is a dehydrating agent .
Drying agents
Sulfuric acid
calcium oxide
anhydrous calcium chloride
;)
-
Never heard of anything called hydrating agent. Dehydrating agent removes water of crystallisation from a hydrated salt.
Eg : Sulfuric acid removes water of crystallisation from hydrated copper(II) sulfate
Also, Phosphorus pentoxide, obtained from the decomposition of aluminium phosphate is a dehydrating agent .
hydration means adding water. so water is a hydrating agent
-
chem p6 2006 oct/nov q6b
Thanks
Umm, use chromatography. Use ETHANOL as solvent as pigments are SOLUBLE IN ETHANOL not water. Then you explain the base line, how it rises up, and shows various spots on the chromatogram. You count them to get the number of different dye solid pigments in paint.
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Drying agents
Sulfuric acid
calcium oxide
anhydrous calcium chloride
;)
temme an experiment to prove dat
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Drying agents
Sulfuric acid
calcium oxide
anhydrous calcium chloride
;)
but whats for what ..6394 said earlier but i frogot to wrte down..
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A@di Thanks for the explanations, but one thing when a salt is in aqueous for then it is soluble but not all solubles are in aqueous form (dissolve in water)?
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Can someone answer this question please?
"calcium carbonate is found in egg shells. All carbonates react with HCL to form chlorides. Calcium carbonate is insoluble in water but calcium chloride is soluble. Most impurities in egg shells are insoluble. Plan an experiment to find out if egg shells are 100% calcium carbonate"
This is the last question in Nov 2000 paper 6 and it is worth 6 marks.
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chem p6 2006 oct/nov q6b
Thanks
Dissolve the solid in an organic solvent. Add a drop of it to the chromatogram. Commence Chromatography with a solvent.
The no. spots created on the chromatogram are the no. of colored substances
@Lariemeeva = Few substances cannot be dissolved by water, meaning they dont exist in the aqueous form. Doesn't mean they are insoluble, they can be dissolved in other organic solvents. For example : The solid from the question i answered above.
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Can someone please tell me what a vacuum pump does ?
I don't really get it and my exam's tomorrow so I'm kinda freaked out ..
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Can someone please tell me what a vacuum pump does ?
I don't really get it and my exam's tomorrow so I'm kinda freaked out ..
it can create a vacuum in any closed container
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can some1 explain how we can make indicator from berries.
i really need..
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Can someone please tell me what a vacuum pump does ?
I don't really get it and my exam's tomorrow so I'm kinda freaked out ..
It sucks all the air in making the container a vacuum (just like on the moon)
Vacuum is an empty is space with no air molecules
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Can someone answer this question please?
"calcium carbonate is found in egg shells. All carbonates react with HCL to form chlorides. Calcium carbonate is insoluble in water but calcium chloride is soluble. Most impurities in egg shells are insoluble. Plan an experiment to find out if egg shells are 100% calcium carbonate"
This is the last question in Nov 2000 paper 6 and it is worth 6 marks.
Take a sample of an egg shell, in a beaker or conical flask preferably. Add to it, excess dilute HCl, and warm to speed up the reaction. Allow calcium carbonate to react with HCl. All the calcium carbonate will produce calcium chloride and CO2 Which will evolve. Add the mixture to water. The calcium chloride will dissolve. Impurities are insoluble. Filter the mixture. If there is a residue, it is an impurity, as is insoluble, proving that the shell is NOT 100% Calcium Carbonate.
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Thanks again A@di
Anyways, I have studied until now:
1. Experimental Techniques
2. Stoichiometry
3. Electricity and Chemistry
4. Chemical Changes
5. Chemical Reactions
6. Acids, Bases and Salts
Are there any other topics I should study for tomorrow (Paper 6), and is there any topic from those that I don't need to focus on much while I'm doing my revision now?
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are there any chances of electrolysis coming in 2morrows ppr?
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can u pls explain me how we can make indicator from berries.?
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^^Yes, huge chances...
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Can someone answer this question please?
"calcium carbonate is found in egg shells. All carbonates react with HCL to form chlorides. Calcium carbonate is insoluble in water but calcium chloride is soluble. Most impurities in egg shells are insoluble. Plan an experiment to find out if egg shells are 100% calcium carbonate"
This is the last question in Nov 2000 paper 6 and it is worth 6 marks.
Take an egg shell and weigh it. Mass of egg shell = Xg
React the egg shell with HCl = Will produce Calcium chloride and CO2.
Filter. Residue = Insoluble impurities and CaCO3
Weigh the Calcium Chloride. Mass of calcium chloride = Yg
Mass of CaCO3 + Impurities = Zg
CaCO3 (100g) --> CaCl2 (111g) + CO2 + H2O
111g of CaCl2 --> 100 grams of CaCO3
Yg of CaCl2 ---> W grams of CaCO3.
% of CaCO3 in egg shels = W grams/Z grams * 100.
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can u pls explain me how we can make indicator from berries.?
i dont think they'll ask u 2 how to make an indicator
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can u pls explain me how we can make indicator from berries.?
Crush the berries. Mix them with water and warm the mixture. Stir. Filter.
Try the indicator on acid/base and check if it showing different colors.
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Crush the berries. Mix them with water and warm the mixture. Stir. Filter.
Try the indicator on acid/base and check if it showing different colors.
thank u so much. :)
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Can anyone help with this
Anyways, I have studied until now:
1. Experimental Techniques
2. Stoichiometry
3. Electricity and Chemistry
4. Chemical Changes
5. Chemical Reactions
6. Acids, Bases and Salts
Are there any other topics I should study for tomorrow (Paper 6), and is there any topic from those that I don't need to focus on much while I'm doing my revision now?
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http://www.chemactive.com/labs/igcse_labs.html this is a link 2 most of de practical expermient might be help ful 4 p6 chem 2 moro
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It sucks all the air in making the container a vacuum (just like on the moon)
Vacuum is an empty is space with no air molecules
Thanks :)
Good luck :D
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can any 1 explain me what is the difference between cathode and anode
good luck to all
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can any 1 explain me what is the difference between cathode and anode
good luck to all
cathode is the negative eletreod which attract CATIONS WHO ARE +
anode is the posotive elctrode which attact teh ANIONS who are -
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whats extrapolation?
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I'm just wasting my time and effort here.
Since A@di, 'Global Moderator', is here to answer all questions as accurately as they can be answered, because he's already been gifted an A* before hand, I guess no one here will go un answered, so It'll hardly make a difference if I leave.
Besides, apparently, my answers are all 'wrong' anyway, which is why he feels the need to re answer the questions I answered.
So, bye folks! And umm, BEST OF LUCK FOR TOMORROW! :D
Good Luck! It'll be easy InshAllah! :)
Laters.
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whats extrapolation?
Extending the graph/line/curve roughly as an estimate to reach an answer. Like, extending the curve roughly in the same direction to predict what will happen at a greater temp. Etc.
And also, showing your working lines. etc.
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I'm just wasting my time and effort here.
Since A@di, 'Global Moderator', is here to answer all questions as accurately as they can be answered, because he's already been gifted an A* before hand, I guess no one here will go un answered, so It'll hardly make a difference if I leave.
Besides, apparently, my answers are all 'wrong' anyway, which is why he feels the need to re answer the questions I answered.
So, bye folks! And umm, BEST OF LUCK FOR TOMORROW! :D
Good Luck! It'll be easy InshAllah! :)
Laters.
Please try your best to stay for as long as possible. You're doing a great job, and none of ur answers are incorrect till now. It will make a hell lotta difference if u leave.
Good luck to you too. Im pretty sure u'll do well. :)
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Extending the graph/line/curve roughly as an estimate to reach an answer. Like, extending the curve roughly in the same direction to predict what will happen at a greater temp. Etc.
And also, showing your working lines. etc.
o ok cheers
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Sorry for the bother again, but I'm still hoping someone can help with this...
Thanks again A@di
Anyways, I have studied until now:
1. Experimental Techniques
2. Stoichiometry
3. Electricity and Chemistry
4. Chemical Changes
5. Chemical Reactions
6. Acids, Bases and Salts
Are there any other topics I should study for tomorrow (Paper 6), and is there any topic from those that I don't need to focus on much while I'm doing my revision now?
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Sorry for the bother again, but I'm still hoping someone can help with this...
Its better if u dont skip important and "not-so-important" chapters for paper 6. Learn all of 'em...anything can come up. CIE is evil
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november 2001 Chemistry paper 6
5 c
why does it look brown?
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2001%20Nov/0620_w01_qp_6.pdf
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^^I can't agree more.
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november 2001 Chemistry paper 6
5 c
why does it look brown?
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2001%20Nov/0620_w01_qp_6.pdf
The light green precipitate slowly turns brown (looks dirty green)
This is the observation of Fe(ii) test.
"Dirty-green precipitate, turning brown on standing: Fe2+"
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m/j 06 p6 q3 d and e plz
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november 2001 Chemistry paper 6
5 c
why does it look brown?
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2001%20Nov/0620_w01_qp_6.pdf
Due to contact with the air (O2), of the surface, the iron (II) oxidizes to iron (III), which turns from a dirty green to brown colour, as Iron (III) is red-brown.
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It turns brown because it changes from Iron(II) hydroxide(which is green) to Iron(III) hydroxide(which is brown)
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Due to contact with the air (O2), of the surface, the iron (II) oxidizes to iron (III), which turns from a dirty green to brown colour, as Iron (III) is red-brown.
so iron(ii) compounds are unstable??
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The light green precipitate slowly turns brown (looks dirty green)
This is the observation of Fe(ii) test.
"Dirty-green precipitate, turning brown on standing: Fe2+"
thats not in any textbook i have
where did you get this?
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m/j 06 p6 q3 d and e plz
???
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???
Join the first three points to form one straight line and extend the line throughout.
Join the last three points to form another line and extend.
Where they intersect, at about 50 deg. C, is the maximum temp. reachable.
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yes, just wat shaizzzle said..check the graph.
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thats not in any textbook i have
where did you get this?
It is ritten in the textbook i have.
Roger Norris, Roger Stanbridge. Pblisher : Nelson Thornes.
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hey guys could you please give me a detail about what happens in benedict test related questions for paper 3. i haven't done practiclesof bio at all and have to give exam tommorow..lol
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winter 09 p6 doubt in q4 (e) (ii)&(iii) i noe the ans i cheked the ms but i didnt understand how??????
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It is ritten in the textbook i have.
Roger Norris, Roger Stanbridge. Pblisher : Nelson Thornes.
whats the title? is it an old book?
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winter 09 p6 doubt in q4 (e) (ii)&(iii) i noe the ans i cheked the ms but i didnt understand how??????
and also q 5 d ii
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winter 09 p6 doubt in q4 (e) (ii)&(iii) i noe the ans i cheked the ms but i didnt understand how??????
cud u plz upload the paper?
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whats the title? is it an old book?
CHemistry for IGCSE. no its not old.
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what is the aim of using dry cotton wool and wet cotton wool ?
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if i use mg powder insted of mg ribbon with same vol and conc of acid
the rate will increase but will the total temperture rise at the end of reaction incrase?
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CHemistry for IGCSE. no its not old.
can you post the page with the detailed tests please(scanned)? it would really help :) :)
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(2)
mg powder has larger s.a to react than magnesium ribbon!
large s.a = more reactant particles in contact..therefore more collisions ..therefore faster rate..faster temp chnages
when you double the volume ..the heat has to spread over a larger volume..therefore the temp chang is less
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d is easy..L IS NAOH
what is teh cu test? NAOH blue ppt..
and aluminute white ppt..whic dissolves in excess givng colourless solution
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Guys, in chem, when they ask you to draw a "smooth line", i saw in the marking schemes, that they draw curves. How the hell are we supposed to know that they mean curve when they themselves have stated that we draw a smooth line?! ???
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NOV 2000 PAPER 6 chem: Q3 B(ii) i dont understand y is it drwn over the original line aint it less soluble so it take more time to crystalise so this means as time increase temp decrease r8????!!!!
thts y i hate teacher made ms not sure of its answer i wish u cn get me original ms if u can also THX IN ADVANCE
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@Fastal - im not sure i can do that now...my scanner is in my parent's room...and they're sleeping now...i hope i cud help, ill definitely try though..
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wats de differenece in heating and warming HELP ??? ??? ???
thanz
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Can anyone plz tell me wtf is the diff between Galvanising and Sacrificial protection???? >:(
Thank you :)
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Guys, in chem, when they ask you to draw a "smooth line", i saw in the marking schemes, that they draw curves. How the hell are we supposed to know that they mean curve when they themselves have stated that we draw a smooth line?! ???
smooth line means to draw a smooth curve. it means not draw a crooked line with a ruler.
if the question says straight line,then need to use ruler.
:D
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wats de differenece in heating and warming HELP ??? ??? ???
thanz
Heating is to give it energy to the boiling point. Warming is little energy
No srry wait. Heating is to give it lots of energy (like about 70 or warever) but warming is little (like maybe 20C) u get what i mean?
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NOV 2000 PAPER 6 chem: Q3 B(ii) i dont understand y is it drwn over the original line aint it less soluble so it take more time to crystalise so this means as time increase temp decrease r8????!!!!
thts y i hate teacher made ms not sure of its answer i wish u cn get me original ms if u can also THX IN ADVANCE
IF ITS LESS SOLUBE IT MEANS THAT IT DISSOLVES AT HIGHER TEMPERATURES.
THEREFORE WHEN YOU COME TO COOL IT DOWN... IT CRYSTALLISES AT HIGHER TEMPERATURE ..THATS WHY ITS ABOUVE!! CZ CRYSTALS APPEARS AT HIGHER TEMPERATURES
SI?
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Hello.............
can sumone help me in chem??
im always confused when to use "warm" the solution or "heat" the solution.
i tot it did not matter.apparently it does.
how do you know which one to use?
thanks!!
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if i use mg powder insted of mg ribbon with same vol and conc of acid
the rate will increase but will the total temperture rise at the end of reaction incrase?
someone asnwer my question! Please? ::)
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I dont think so..because the no. of particles of Mg reacting with the acid will be the same..
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@ kimo-no the final temperature will remain the same
the only difference wud be that the final temp wud be reached faster wen compared to the ribbon
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if i use mg powder insted of mg ribbon with same vol and conc of acid
the rate will increase but will the total temperture rise at the end of reaction incrase?
someone asnwer my question! Please? ::)
I think so... because there will be more collision and reaction. Not sure tho;)
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Can anyone plz tell me wtf is the diff between Galvanising and Sacrificial protection???? >:(
Thank you :)
Anyone ?
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whats the difference between corrosion and rusting??
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I dont think so..because the no. of particles of Mg reacting with the acid will be the same..
ok well in nov 09
it says HIGHER TEMP CHANGES ..BUT IGNORE RATE? why??
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whats the difference between corrosion and rusting??
Corrosion is for any metal. Rusting is for Iron and Steel
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Can anyone plz tell me wtf is the diff between Galvanising and Sacrificial protection???? >:(
Thank you :)
Galvanised steel is steel coated with zinc. The zinc coating stops water and oxygen from reaching the steel. But even when the zinc is scratched, the steel underneath will not rust. So there must be another way in which the zinc protects the steel. This is Sacrificial Protection.
Zinc is more reactive than iron. A more reactive metal loses eelectrons and forms positive ions more easily than a less reactive metal. When the layer of zinc is scratched, a sort of electrochemical cell is set up in the presence of moisture. The electrons flow from the zinc to the iron. The zinc is oxidized and thus corrodes rather than iron.
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Mg RIBBON with 20 cm3 of HCl - Say temperature difference 15 deg. C
Mg POWDER with 20 cm3 of HCl - Temp difference greater than 15 deg. C. MAY be double. Not necessarily. BUT MORE TEMP DIFF.
4g Mg + 20 cm3 of HCL - say temp diff 15 deg. C.
8g Mg + 20 cm3 of HCl - DOUBLE temp diff - 30 deg. C
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Anyone ?
i think both are the same.
its just that galvanizing does not require electrochemical deposition.
:D
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IF ITS LESS SOLUBE IT MEANS THAT IT DISSOLVES AT HIGHER TEMPERATURES.
THEREFORE WHEN YOU COME TO COOL IT DOWN... IT CRYSTALLISES AT HIGHER TEMPERATURE ..THATS WHY ITS ABOUVE!! CZ CRYSTALS APPEARS AT HIGHER TEMPERATURES
SI?
man i dont understand expirment really XD cn u give it a quick explanation
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Galvanised steel is steel coated with zinc. The zinc coating stops water and oxygen from reaching the steel. But even when the zinc is scratched, the steel underneath will not rust. So there must be another way in which the zinc protects the steel. This is Sacrificial Protection.
Zinc is more reactive than iron. A more reactive metal loses eelectrons and forms positive ions more easily than a less reactive metal. When the layer of zinc is scratched, a sort of electrochemical cell is set up in the presence of moisture. The electrons flow from the zinc to the iron. The zinc is oxidized and thus corrodes rather than iron.
In other words, Galvanising is coating it, and Sacrificial is the process after the coating is removed...
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mention impermeable and protective layer
ZINC OXIDE
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Mg RIBBON with 20 cm3 of HCl - Say temperature difference 15 deg. C
Mg POWDER with 20 cm3 of HCl - Temp difference greater than 15 deg. C. MAY be double. Not necessarily. BUT MORE TEMP DIFF.
4g Mg + 20 cm3 of HCL - say temp diff 15 deg. C.
8g Mg + 20 cm3 of HCl - DOUBLE temp diff - 30 deg. C
wrong..just a faster rate..but same final temp
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wrong..just a faster rate..but same final temp
Yeah! Umm, that was supposed to be a question!
I forgot to write, 'please correct if wrong'. :P
Thanks! ;)
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man i dont understand expirment really XD cn u give it a quick explanation
imagine dissolving something very solubel in water and heating!..it will dissolve early at 20 * c
imagine dissolivng soemthin not so soluble in water and heating..it will disolve late at 40 *
now imagine the temp is 100* when cooling down..which 1 will appear first..the less soluble !!!!!! get it?
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Heating is to give it energy to the boiling point. Warming is little energy
No srry wait. Heating is to give it lots of energy (like about 70 or warever) but warming is little (like maybe 20C) u get what i mean?
so how do we know when to use warm or when to use heat?
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wrong..just a faster rate..but same final temp
so....greater/higher temp. change, they mean the final temperature rite??
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imagine dissolving something very solubel in water and heating!..it will dissolve early at 20 * c
imagine dissolivng soemthin not so soluble in water and heating..it will disolve late at 40 *
now imagine the temp is 100* when cooling down..which 1 will appear first..the less soluble !!!!!! get it?
yh Thank You man i was thinking about it (i hate tht teacher made ms cn u upload me the original if u got it?)
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yeh if the surface area increases the final temperature after a specific time must not change.....example if we use Mg ribbon and the temp difference after 2 minutes is 15...for Mg powder it will be more than 15 as rate of reaction increases
but after all Mg is used up and if the mass of Mg is equal in both experiments the final temp wont change....
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Abbay, in cheezoon pe sar khapanay se behtar hai ja ke pp karo.
Wo ye poochain ge nahin. :S
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Final temperature means temperature after the reaction has stopped
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ok well in nov 09
it says HIGHER TEMP CHANGES ..BUT IGNORE RATE? why??
this is wat the "er" says..
Candidates found this difficult and it was a good discriminator. Many candidates thought that the
temperature change would be the same or lower. Vague answers discussed the rate of the
reaction and did not answer the question.
probably thats y they wrote "ignore rate"
@Shaizzzle - LOL@"khapanay se" ... u too from india?? mumbai?
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so....greater/higher temp. change, they mean the final temperature rite??
nope!
the temperature change in a second
for example temp increase by 1 is 1 sec with mg ribon
temp increas e by 5 is 1 sec with mg powder ( but this reaction will finish faster )
but the final temp will be the same!
si?
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anybody doing paper 5 tomorrow?
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_5.pdf
q2 g and h
how can one identify transition metals, more specifically manganese oxide?
also, whats the test that identifies oxide ionS?
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this is wat the "er" says..
Candidates found this difficult and it was a good discriminator. Many candidates thought that the
temperature change would be the same or lower. Vague answers discussed the rate of the
reaction and did not answer the question.
probably thats y they wrote "ignore rate"
@Shaizzzle - LOL@"khapanay se" ... u too from india?? mumbai?
Umm.... PAKISTAN! PAKISTAN! PAKISTAN! MUSLIM!
I swear, why does EVERYONE assume India?! :@
And I've lived in Saudi Arabia for 12 years, and still do, before you go making incorrect assumptions. :/
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Increasing the concentration of the solute and solvent will make the reaction faster
Increasing the AMOUNT of the solute will make it faster but increasing the amount of the solvent will make it take longer...
RIGHT???????
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cud u plz upload the paper?
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Nov/0620_w09_qp_6.pdf
its q 4 e ii and iii
and q 5 d ii
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anybody doing paper 5 tomorrow?
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_5.pdf
q2 g and h
how can one identify transition metals, more specifically manganese oxide?
also, whats the test that identifies oxide ionS?
Transition metals have a very unique property .. i.e they are "Coloured".
Here, solid S was black, again a color.
Also, Most of the transition metals are catalysts...here test (e) says hydrogen peroxide was added and rapid effervescence was observed. Meaning, the catalyst/transition metal helped in the decomposition of H2O2
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Nov/0620_w09_qp_6.pdf
its q 4 e ii and iii
and q 5 d ii
Shaizzzle and Kimo Jesus answered
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Umm.... PAKISTAN! PAKISTAN! PAKISTAN! MUSLIM!
I swear, why does EVERYONE assume India?! :@
And I've lived in Saudi Arabia for 12 years, and still do, before you go making incorrect assumptions. :/
Sorry, didnt know that. No intentions of making incorrect assumptions. Apologies.
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KIMO SAME EXAM SAME QUESRION d XD
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nope!
the temperature change in a second
for example temp increase by 1 is 1 sec with mg ribon
temp increas e by 5 is 1 sec with mg powder ( but this reaction will finish faster )
but the final temp will be the same!
si?
So final temp IS THE SAME RIGHT???
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Abbay, in cheezoon pe sar khapanay se behtar hai ja ke pp karo.
Wo ye poochain ge nahin. :S
hey tumhare asli nam kiya hai?
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Transition metals have a very unique property .. i.e they are "Coloured".
Here, solid S was black, again a color.
Also, Most of the transition metals are catalysts...here test (e) says hydrogen peroxide was added and rapid effervescence was observed. Meaning, the catalyst/transition metal helped in the decomposition of H2O2
umm okay thanks :)
but how does "oxide" come in the results for solid S?
cuz i though that since oxide is present in hydrogenperoxide, so its not going to be there in S...
HELP!! PLEAASSEE!
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Nov/0620_w09_qp_6.pdf
its q 4 e ii and iii
and q 5 d ii
e(i) Greater Temp. Change (BECAUSE it was in POWDER form, thus increasing the surface area, and so therefore faster reaction, producing a greater final temperature in the same time. Kimo has a point there. BUT this one is confirmed from the mark scheme)
e(ii)Half the temp change i.e 7.5 deg. C (as vol of acid is double)
5 d(ii) White precipitate which dissolves in excess (because this is NaOH. L is NaOH.)
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why does an increase in volume lead to a decrease in temperature change?
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e(i) Greater Temp. Change (BECAUSE it was in POWDER form, thus increasing the surface area, and so therefore faster reaction, producing a greater final temperature in the same time. Kimo has a point there. BUT this one is confirmed from the mark scheme)
e(ii)Half the temp change i.e 7.5 deg. C (as vol of acid is double)
5 d(ii) White precipitate which dissolves in excess (because this is NaOH. L is NaOH.)
i didnt get e ii
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in biology do we find the uncertainty the same way that we do in physics?? for example for practicals they sometimes ask for uncertainty. so should i give it as (+-least count)?
P.S sahi baat hai itna mat khapo questions par...lol.
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why does an increase in volume lead to a decrease in temperature change?
Because,
Imagine you've got the same Mg and 20 cm3 of acid.
Now, if you take the same amount of Mg, but DOUBLE the acid, 40 cm3,
There is MORE acid than before.
So, a greater volume of acid with which the Mg needs to react, i.e double, so half the temp. change.
The TOTAL temp change is brought about by the COMPLETE reaction.
If the acid volume is doubled, that means the quantity of Mg needed is halved as well.
If the vol is doubled, the quantity of Mg ALSO has to be doubled to get the same temp change.
Greater volume, more time to react with all of it. So, only half the job done, thus only half the temp change.
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Hello.............
can sumone help me in chem??
im always confused when to use "warm" the solution or "heat" the solution.
i tot it did not matter.apparently it does.
how do you know which one to use?
thanks!!
-
ana ma3afi ma3loom. :(
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Hello.............
can sumone help me in chem??
im always confused when to use "warm" the solution or "heat" the solution.
i tot it did not matter.apparently it does.
how do you know which one to use?
thanks!!
see it totally depends on the q and wat is the eperiment abt.....for example if u aretesting for nitrate u dont heat u warm it...bla bla just remember tht heating is a faster increase in temp ...and rest if u have brains u can distinguish and ans well....:D
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Because,
Imagine you've got the same Mg and 20 cm3 of acid.
Now, if you take the same amount of Mg, but DOUBLE the acid, 40 cm3,
There is MORE acid than before.
So, a greater volume of acid with which the Mg needs to react, i.e double, so half the temp. change.
The TOTAL temp change is brought about by the COMPLETE reaction.
If the acid volume is doubled, that means the quantity of Mg needed is halved as well.
If the vol is doubled, the quantity of Mg ALSO has to be doubled to get the same temp change.
Greater volume, more time to react with all of it. So, only half the job done, thus only half the temp change.
What about the speed?
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see it totally depends on the q and wat is the eperiment abt.....for example if u aretesting for nitrate u dont heat u warm it...bla bla just remember tht heating is a faster increase in temp ...and rest if u have brains u can distinguish and ans well....:D
i c...
thanks!!!!:D
but it still means i need to either memorize or understand wat im doing though.:P
sigh...but thanks!
;D
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Because,
Imagine you've got the same Mg and 20 cm3 of acid.
Now, if you take the same amount of Mg, but DOUBLE the acid, 40 cm3,
There is MORE acid than before.
So, a greater volume of acid with which the Mg needs to react, i.e double, so half the temp. change.
The TOTAL temp change is brought about by the COMPLETE reaction.
If the acid volume is doubled, that means the quantity of Mg needed is halved as well.
If the vol is doubled, the quantity of Mg ALSO has to be doubled to get the same temp change.
Greater volume, more time to react with all of it. So, only half the job done, thus only half the temp change.
just one small doubt.igot most of u....but still if the acid has doubled...it means tht 20cm3 of it is in excess and the rest of the reaction is still the same nuthin has mainly changed it is just tht there is less water and more glases to be filled.y would the rate or ane thnid change..the glasses are extra
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i have noticed tht all pprs have the q 5 on test for cations and anions....it is so weired.:S
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paper 5 and 6 is all about them ..
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p6 chm nov2000 3 D
pls some one xplain it to me plsss and the answer
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p6 chm nov2000 3 D
pls some one xplain it to me plsss and the answer
remember whn i said less soluble and more solube?
crystas would appear at lower temp becaz they dissolve at lower temp
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remember whn i said less soluble and more solube?
crystas would appear at lower temp becaz they dissolve at lower temp
i know wht u answer is B i need D he use 2.5g instead of 5g so wht temp change??? SO CN U EXPLAIN TO ME Y IT REDUCED???
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_6.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_6.pdf)
5)c)ii) How does the mark scheme say blue ppt. Copper isnt soluble in excess........
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i know wht u answer is B i need D he use 2.5g instead of 5g so wht temp change??? SO CN U EXPLAIN TO ME Y IT REDUCED???
its has nothing to do with temperature change..
it says how would the results difer
can u tell me wht the answer in the mark scheme is?
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TEMP BE LOWER
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_6.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_6.pdf)
5)c)ii) How does the mark scheme say blue ppt. Copper isnt soluble in excess........
it is solube in excess with ammonia forming a dark blue solution
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_6.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_6.pdf)
5)c)ii) How does the mark scheme say blue ppt. Copper isnt soluble in excess........
action with aq. ammonia gives light blue ppt.. and copper is soluble in access aq. ammonia gives royal bule
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TEMP BE LOWER
yea caz 2.5g of it..dissovles at 25 * c
and 5g of it wil dissolve at 50 * c
so when will the crystalls appear..at a lower temperate..25..
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_6.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_6.pdf)
5)c)ii) How does the mark scheme say blue ppt. Copper isnt soluble in excess........
copper...
with sodium hydroxide ...light blue ppt...insoluble in excess
with amonia...light blue ppt...soluble in exsecc givin royal blue solution..:d
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action with aq. ammonia gives light blue ppt.. and copper is soluble in access aq. ammonia gives royal bule
srry i meant (i)
By the way u like my new signature :D
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srry i meant (i)
By the way u like my new signature :D
yep awsome (
1) WHAT?
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yea caz 2.5g of it..dissovles at 25 * c
and 5g of it wil dissolve at 50 * c
so when will the crystalls appear..at a lower temperate..25..
HMM I DON GET IT as the mass no relation between temp so wht made this go to tht if it says rate or something thn thts ok no arguement (tht ms have mistakes as it test if water is pure with cobalt chloride nonsense as it is measured by the boiling point daaaaah)
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srry i meant (i)
By the way u like my new signature :D
yea so it is light bule ppt.
LOL @ sig. LMAO !!
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srry i meant (i)
By the way u like my new signature :D
how much tyme u have for all tht ane ways..if sumthin is insoluble...wat does it mean.....it means tht it will be left at the botom of the beaker..and it is bue in colour in this case....:D
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yea so it is light bule ppt.
LOL @ sig. LMAO !!
Owkay... thx guys :)
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Owkay... thx guys :)
still LMOA .. =P
XD
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still LMOA .. =P
XD
HEHEHHE xD See how we are treated like sh*t xD
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Everyone done?
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Everyone done?
yep
good night and good luck mr . india! uae annonymous
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yep
good night and good luck mr . india! uae annonymous
It's Pakistan, actually. :P
And KSA, not UAE. XD
Luck!
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june 1998 3c p6 help help :)
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plz help in nov 2004 q 5 ii ammonium chloride was added to lead nitrate in markscheme it says white ppt how come when it is lead not silver nitrate
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the chlori(n or d not sure)e test
acidify with dilute nitric acid and add silver nitrate or lead nitrate
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GOOD LUCK IN CHEM EVERYONE!!!!!!!
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chemistry paper 6 done! cross out from the list .
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chemistry paper 6 done! cross out from the list .
ya lol
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my exam is in 4 hours..sick of waiting...hate aftrnoon exams :@
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my exam is in 4 hours..sick of waiting...hate aftrnoon exams :@
ditto ....but i suggest u do a lil math if it's ur soo bored :P :P :P ::)
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7.how to detect transpiration (place a plastic bag on the plant ,water will condense)
8.effect of cutting roots of a seedling (wilts when cut , when not cut is healthy and upright)
9.effect of cutting roots of a plants on it's water uptake
10.u gotta what a bill jar is and thatit's used for testin for breathing
11. test for the different scents of plants and the effect of it on attracting insects (i wanna describe the exp but it's too long and i'm busy . sooo google it or smthn , k?)
12.test for the effect of colour of petal of a flower on the attracting of insects (google this too! )
13.exp on pulse rate of a runner and person whose not doin excersice
14.testin of carbon dioxide, and oxgen
15.test of finding the reaction time of a person
16.tests abt the effect of auxin on phototropism, and Geotropism
later ;)
Thanks sooo much golden girl thts soo nyc of u!!!....XD
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ditto ....but i suggest u do a lil math if it's ur soo bored :P :P :P ::)
naah
im doin every last question from every past paper lol
then ill do all teh analyis :P
bbye :) wish me luck and pray for me ! :-\
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good luck kimo jesus u can do it...and i agree with wat the golden girl had said .....tht u did help her as she revised everything from ur notes at last moment!!..evn i did tht!!!....good work!!...keep it up!!
and ya =Rep for the golden girl...the bio answer...Thanks agn.:P :D
@the golden girl: By the way which subjs r u doing ...??
;)
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i meant +Rep*.lol.... :P
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naah
im doin every last question from every past paper lol
then ill do all teh analyis :P
bbye :) wish me luck and pray for me ! :-\
cool then lol
Talk to you later ........ sure thing kimo ..............By the way when u go for the exam just chill k ....don't be nervous ;)
gd luck to u
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How does one work out the volume of a certain thing on a graph after a certain time? how does one predict the temperature and last but not least how would you sketch the graph after certain amount of a certain acid is used, i mean how do you put the line and stuff.
And thats it, now i have to just memorize the table fully, read kimbo jesus's notes, eat, pray and go kill the exam.
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how do we get copper from malachite???
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there are quite a lot
http://en.wikipedia.org/wiki/Copper_extraction_techniques
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woah
I POWNED THE EXAM :d
thank you lord!
thank u all for ur help
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woah
I POWNED THE EXAM :d
thank you lord!
thank u all for ur help
:D:D:D:D:D
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how to extract copper from copper carbonate......
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heat copper carbonate , carbon dioxide evolved, left is copper oxide
Reaction::
CuCO3 (s) ===> CuO (s) + CO2 (g)
Pass hydrogen gas oven red hot copper oxide, combines with oxygen to form water (steam)
Reaction::
CuO (s) + H2 (g) ===> Cu (s) + H2O (g)
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Hey . guys .. i have the bio paper 6 tmrw . and i dnt undestand a thing.. how do i draw .. the section of a garlic or apple or spmething .. i still dont get it at all ??? paper 6 bio may june 2009 biology number 1 ?
rsvp
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Hey . guys .. i have the bio paper 6 tmrw . and i dnt undestand a thing.. how do i draw .. the section of a garlic or apple or spmething .. i still dont get it at all ??? paper 6 bio may june 2009 biology number 1 ?
rsvp
lol the garlic question that was my board paper
i remember i had to draw it thrice to get it right the complete examination hall was erasing and drawing the last half hour
fun day lol
well u have to be very neat in ur drawings make sur to make it enlarged if it is said in the question the difference between 2 membranes should be the same as the diagram like if in the diagram sum parts are thick and sun thim that is how ur drawing shud have as well
if they have asked u to label dont forget to do it
just make ur drawing as neat as u can
if u wanna know more tell me and practice past papers
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.. i dunno how to draw it .. like cn u email me the drawing .. plz .. if u need my email ..i guess u cn find it on my profile .. .Thanks a lot .. i just cant draw it
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ok i cant do it now but ill do it by today il send it by evening
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okay. Thanks a lot .. am counting on you 4 that ,, am gna w8 ,,, Take care
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okay. Thanks a lot .. am counting on you 4 that ,, am gna w8 ,,, Take care
i m really sorry but i just cant seen to get it right
so i cant help ya there
and i have to study for my paper but ill see if i can get it
maybe sum1 else can help ya
sorry
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its okay .. Thanks anyway., .i wont give up .. and am gonna try my best :)
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i m really sorry but i just cant seen to get it right
so i cant help ya there
and i have to study for my paper but ill see if i can get it
maybe sum1 else can help ya
sorry
yea i'll do that .. im alive .. best of luck for ur paper .. !!
@Lonely gimme 2 mins .. ;)
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yea i'll do that .. im alive .. best of luck for ur paper .. !!
@Lonely gimme 2 mins .. ;)
hey thanks i was feeling guilty for not being able to help
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hey thanks i was feeling guilty for not being able to help
please check !! i know looks a but scary .. :P :P believe me looks better on paper =]
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ok yea sure thanks forgot the multiple arrows ;)
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Could some1 tell me wat should i study for the bio paper 6 tomoro... i will solve past papers but i need to wat are the stuff i should no... :D
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Could some1 tell me wat should i study for the bio paper 6 tomoro... i will solve past papers but i need to wat are the stuff i should no... :D
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Read experiments from your book .. after having solved most of the papers try to figure out wat topics havnt been covered in the past and learn them well .. im still solving papers and will let know if i find anything appropriate ;)
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Read experiments from your book .. after having solved most of the papers try to figure out wat topics havnt been covered in the past and learn them well .. im still solving papers and will let know if i find anything appropriate ;)
isn't there some kind of "shortcut" like notes or something? because i'm a very lazy studyer.. i hate it
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Nop no shortcuts .. post in references and resources for some notes .. i had a lot of stuff in biology last year .. all gone because i formatted my pc !! sorry =\
see if u get something from here
http://freeexampapers.com/Dndex.php?d=SUdDU0UvQmlvbG9neS9DSUUvUmVzb3VyY2Vz
^^biology resources
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please check !! i know looks a but scary .. :P :P believe me looks better on paper =]
hey!Im sorry to just barge in like this,
there's a mistake on your drawing! :o
i dont know if you know this, but when it comes to drawing, we should not make like a line above another line.
the lines should be smooth. n yea!they will penalize the mark if drew double line.
i didnt know about this too,until we went through the examiners' report!
hehe... :D
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@~VIN1094~:
are you studying for bio paper 5 or 6?
he's takin papr 6 tom and he already took papr5
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hey!Im sorry to just barge in like this,
there's a mistake on your drawing! :o
i dont know if you know this, but when it comes to drawing, we should not make like a line above another line.
the lines should be smooth. n yea!they will penalize the mark if drew double line.
i didnt know about this too,until we went through the examiners' report!
hehe... :D
OH THANK YOU SO MUCH !! I'll see to it thank u .. ;)
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he's takin papr 6 tom and he already took papr5
umm .. actually i was supposed to take p5 until last year but i chose to take p6 ;) like thers no risk for errors and stuff .. =)
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OH THANK YOU SO MUCH !! I'll see to it thank u .. ;)
no prob!im happy to help! ;)
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ok so i was just wondering, the only really "right" way to study would be to go through ALLLLL the past papers right? because i'm REALLY bad at experiments, i NEVER understand them, and i don't know what to do! i'm a more math-y person, not cut out for the sciences :'( :-X :-[
for paper 6, i guess tat would be the best thing to do!tats what i did for chem!
and they tend to repeat the same question again!so..yea...if you can,do as much past papers as u can! :)
help you to understand better too! ;D
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@SNA: thanks
Also, can anyone please explain the purpose of a water bath? I don't get what it is, what does it do? I've never done this stuff before, never even heard of a WATER BATH!
When you want to heat the reagent in a test tube, instead of directly heating it over the bunsen burner, you use a beaker filled with boiling water, and you place the test tube in that beaker, rather than heating it directly.
This beaker is called the 'water bath'.
It's mostly used as a safety precaution to avoid test tube from cracking on direct contact. Also to allow even heating as the entire water is heated equally and so all the contents of the test tube may indirectly be heated, safely.
Especially when heating flammable liquids, such as ethanol, which may ignite on direct heat or flame contact, a water bath is used, as a safer indirect way of 'smooth' heating.
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So, Vin, got any notes or requirements for the bio practical paper that may be of use to us? Thanks! :)
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So, Vin, got any notes or requirements for the bio practical paper that may be of use to us? Thanks! :)
im sorry i had some great ones .. lost them last year !! jus a couple of presentations .. no use for p6 =\ sorry ..
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So, what do we have to revise? :S
Umm,
1. Food Tests
2. Classification of organisms
3. Sexual and Asexual reproduction in plants
4. Seed Germination
5. Transpiration
6. Magnification: Length of image/length of object.
Note: If the object HAS ALREADY BEEN MAGNIFIED. i.e If the object has also written next to the picture, x300 or similar, and they ask you to find the magnification of the REAL THING, then, you use:
Magnification=Length of image/length of object X magnification of object
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Shazizzle: What are the main stuff under the following topics~
1. Classification of organisms
2. Sexual and Asexual reproduction in plants
3. Seed Germination
4. Transpiration
I'm really bad at experiments. :( Help, please? Pretty please? :)
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So, what do we have to revise? :S
Umm,
1. Food Tests
2. Classification of organisms
3. Sexual and Asexual reproduction in plants
4. Seed Germination
5. Transpiration
6. Magnification: Length of image/length of object.
Note: If the object HAS ALREADY BEEN MAGNIFIED. i.e If the object has also written next to the picture, x300 or similar, and they ask you to find the magnification of the REAL THING, then, you use:
Magnification=Length of image/length of object X magnification of object
@Shazzizle, please clarify the "Note" part at the bottom (about magnification), I don't understand it :(
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I need november 2001 MS paper 6 biology code 0610 anyone got it? Can you please upload it or give me a link?
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Shazizzle: What are the main stuff under the following topics~
1. Classification of organisms
2. Sexual and Asexual reproduction in plants
3. Seed Germination
4. Transpiration
I'm really bad at experiments. :( Help, please? Pretty please? :)
Yeah, we all are ^^. :/
Well, under classification, we've got the group of invertebrates. i.e The arthropod group. consisting of arachnids, crustaceans, myriapods and insects. I've seen questions in the paper about their external features, so you should revise those.
Then, you can have a look at the vertebrate classes, amphibians, fish, mammals, birds, reptiles. Those are possible.
In plants, you should know the basic methods of Asexual reproduction. They don't usually ask many such related questions, but still, you know, the runners, rhizomes, tubers, corns, bulbs, cutting, grafting etc.
Tubers, i.e the potato has been asked before.
Seed germination is important. You need to know how the dry mass of a seed changes when it germinates.
There's a general trend: The mass initially decreases as the nutrients stored in the seed cotyledon are made us of for growth.
However, once the shoot and leaves develop, the mass then increases, as the plant grows, and also as photosythesis can take place thus producing more glucose which in turn may be used for respiration to form ATP energy and thus growth, so an overall increase in mass.
They've asked quite a lot of questions relating to transpiration. Mainly related to wilting. You need to know turgidity, and thus that the cells are flaccid during wilting i.e plasmolysis has occurred and the plant has lost it's support via the transpiration stream. Then there's knowing of the stomata i.e when they are open and when they are closed.
Recently, there are questions relating to food tests. You need to be able to describe tests.
You can easily gain free marks if you
1. Mention grinding up the samples to increase surface area
2. Talk about taking the same apparatus i.e fair tests and controlled variables for all
3. And repeating for accuracy
4. And if you mention a safety precaution like gloves, water bath, goggles, lab coat etc.
Remember including such points.
And usually, the questions relate to comparison. Comparing one fruit with another. If you see the mark schemes, you'll come to know, that all you have to do is describe what you see. Every detail can be written. Even the size and shape!
Good Luck!
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@Shazzizle, please clarify the "Note" part at the bottom (about magnification), I don't understand it :(
Okay, say there's a picture of an apple.
You've got to draw a larger one.
Then they ask you to measure both the length of the object, AND your image.
Suppose the object is: 5 cm
The image you drew is: 10 cm
Now they ask you to calculate the magnification. Say they tell you that the picture was magnified x100 times. (sometimes they write this statement there. At other times, you have to look carefully at the picture. It usually has x100 or similar written near it.
So, they ask you to find the magnification of THE REAL SIZE OF THE APPLE and the image you've drawn.
So, magnification= image/object X mag. of pic.
= 10/5 X 100
= x200
If, however the pic they give you IS OF THE ORIGINAL SIZE and is not itself initially magnified, you don't need to do this.
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Yeah, we all are ^^. :/
Well, under classification, we've got the group of invertebrates. i.e The arthropod group. consisting of arachnids, crustaceans, myriapods and insects. I've seen questions in the paper about their external features, so you should revise those.
Then, you can have a look at the vertebrate classes, amphibians, fish, mammals, birds, reptiles. Those are possible.
In plants, you should know the basic methods of Asexual reproduction. They don't usually ask many such related questions, but still, you know, the runners, rhizomes, tubers, corns, bulbs, cutting, grafting etc.
Tubers, i.e the potato has been asked before.
Seed germination is important. You need to know how the dry mass of a seed changes when it germinates.
There's a general trend: The mass initially decreases as the nutrients stored in the seed cotyledon are made us of for growth.
However, once the shoot and leaves develop, the mass then increases, as the plant grows, and also as photosythesis can take place thus producing more glucose which in turn may be used for respiration to form ATP energy and thus growth, so an overall increase in mass.
They've asked quite a lot of questions relating to transpiration. Mainly related to wilting. You need to know turgidity, and thus that the cells are flaccid during wilting i.e plasmolysis has occurred and the plant has lost it's support via the transpiration stream. Then there's knowing of the stomata i.e when they are open and when they are closed.
Recently, there are questions relating to food tests. You need to be able to describe tests.
You can easily gain free marks if you
1. Mention grinding up the samples to increase surface area
2. Talk about taking the same apparatus i.e fair tests and controlled variables for all
3. And repeating for accuracy
4. And if you mention a safety precaution like gloves, water bath, goggles, lab coat etc.
Remember including such points.
And usually, the questions relate to comparison. Comparing one fruit with another. If you see the mark schemes, you'll come to know, that all you have to do is describe what you see. Every detail can be written. Even the size and shape!
Good Luck!
Wow... this really helps thx! but one thing: Wht type of questions do they ask for the vertebrate classes dealing with the amphibians, reptiles, fish, mammals and all? Only the external features or anything else in particular?
Thanks! :D
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there is one question in which you have to draw an organism shown in a pic. i am really bad at drawing :(
do u guys hv any points? or am i lost? :(
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anyone..wats the use of a heat screen?? bio question..please repp ASAP!!
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Shazizzzle: thanks a billion! That reaaallly helped me a lot. If I get A* in Biology, I'll owe it all to you. I'm gonna pray hard for you tomorrow. ;D I shall go through the vertabrates, invertabrates, asexual reproduction, and germination now. Everything else, I know. Good night. All the best! God Bless You! :) ? lol
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Shazizzzle: thanks a billion! That reaaallly helped me a lot. If I get A* in Biology, I'll owe it all to you. I'm gonna pray hard for you tomorrow. ;D I shall go through the vertabrates, invertabrates, asexual reproduction, and germination now. Everything else, I know. Good night. All the best! God Bless You! :) ? lol
Good Luck! :) Haha, yeah, no problem. :)
Thanks! :)
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there is one question in which you have to draw an organism shown in a pic. i am really bad at drawing :(
do u guys hv any points? or am i lost? :(
make the drawing big,approximately twice as big.
dont overlap the drawing lines - make smooth line.
dont shade the drawing unless stated ( but so far,i've never found question that asks to shade the drawing).
make a point to label the diagram - atleast 3.
lastly,please draw EVERYTHING you see, even a small circle on a cell for instance. draw it!
thats wat i can think of so far. hope it helped! :)
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can anyone pretty please tell me the function of heatscreen??? :-[
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can anyone pretty please tell me the function of heatscreen??? :-[
Umm, it absorbs the heat from the light source, i.e acts as a filter, preventing heat from passing through. It allows only light intensity to pass through. It is essential in experiments where temperature may affect the results, i.e photosynthesis.
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can someone post the graph for dry mass in germination?
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i gess u should pray for all of us .
well thanx wish for all of us best of luck .
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Umm, it absorbs the heat from the light source, i.e acts as a filter, preventing heat from passing through. It allows only light intensity to pass through. It is essential in experiments where temperature may affect the results, i.e photosynthesis.
ttthhhaaaannnnnnnkkkkkkkksssssss a looooooottttttttt <3<3<3
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So I'm still founded by this idea https://studentforums.biz/index.php/topic,7496.0.html and even though we didn't get a chance to make one for Chemistry, I hope someone checks this out and does the same for Biology.
I'm also looking for some really great links for Bio P6 help, if anyone knows some, It'd be really nice to share them...
And does anyone know if the Past papers ever had the tests for Iodine and the other food tests on the last page of the test just like Physics 2006?
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In M/J 2008 for labeling the tomato (2a), they mention labeling the placenta in the mark scheme. What is a placenta in plants and what exactly are we supposed to label in such a case?
(If fruits other than a tomato are given, we can really only label the seeds and the pericarp right? What else is there?)
Also, completely irrelevant, let's say I get a 20/40 for P6 but do REALLY well in P3 and P1 (safe A's). Do I still have a shot at an A*? ThANKs :)
They refer to that watery part in the middle with the seed branching out on both sides from the center. That looks like a placenta too, so they named it that. :S Weird, I know.
Umm, you can also label the central region i.e the fruit nutrients part, the real thing itself, as the 'endosperm'.
Umm, the percentile is usually at a 29-30/40 for P6. So, if you try exceptionally hard in p3 and p1, you might just get an A*, but As in all are necessary, I guess.
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For M/J/08 Paper 6, Q.3)b)i):
How do we measure the distance grown (mm) accurately from the diagram. The pollen tube is not a straight line so how do we measure it?
Q.3)a)ii)
Where is the micropyle? Is it the whole in between C at the right-hand side? The big hole?
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Also, what is the rough grade boundary for A* with all 3 components combined? How do we calculate it, say for O/N/09.
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Also, what is the rough grade boundary for A* with all 3 components combined? How do we calculate it, say for O/N/09.
It is not like that, there isn't a fixed grade boundary for A*, the top xx % of the candidates in the examination would receive the A* grade ....
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Guys just one final thing, if we're asked to compare say the amount of protein, carbohydrate etc. in something, would it be better to say that for protein say the one which has more protein gives a darker purple colour or would it be better to say that it gets purple first (time period)????
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So I'm still founded by this idea https://studentforums.biz/index.php/topic,7496.0.html and even though we didn't get a chance to make one for Chemistry, I hope someone checks this out and does the same for Biology.
I'm also looking for some really great links for Bio P6 help, if anyone knows some, It'd be really nice to share them...
And does anyone know if the Past papers ever had the tests for Iodine and the other food tests on the last page of the test just like Physics 2006?
I hope someone can actually help before the exam.
-
I hope someone can actually help before the exam.
im sorry cuz i cant help with the notes.
but for the food test,most likely will come.better know it by heart!
good luck! ;)
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magnification=size of image/size of object
big differece between *1 and*100
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hii thanks 4 all ur hard work .. everythings so helpful ..
okie so in may/june 03 q1. (v) can i say .. that sample C contains substance X which might be a catalyst that helped in speeding up the reaction. ?? or any1 has better ideaa??
and for 3 a (ii) .... in the markscheme they times the length of drawing/ length of animal by 1.5 ... why is that??
thanks in advance .. ;)
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hii thanks 4 all ur hard work .. everythings so helpful ..
okie so in may/june 03 q1. (v) can i say .. that sample C contains substance X which might be a catalyst that helped in speeding up the reaction. ?? or any1 has better ideaa??
and for 3 a (ii) .... in the markscheme they times the length of drawing/ length of animal by 1.5 ... why is that??
thanks in advance .. Wink
q1(v) is correct(i think so)
and for 3a ur diagram should be 1.5 times larger
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No Genatics, Ecology ( Food diagram, carbon cycle) and stuff like that in paper 6 right?
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No Genatics, Ecology ( Food diagram, carbon cycle) and stuff like that in paper 6 right?
no
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Hey guys... i got this doubt. Whts the difference between a calyx and sepals? :S
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Prolly im late .. there is no difference in fact they are the same .. calyx is the outermost whorl of a flower.. it consists of sepals usually green corolla is the whorl of petals
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chem bio or both ??
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Hi guys. I did Bio paper 5 today. Anyone else done it? It was great! =)
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I knw oct/nov was really hard .. i'd solved it without studying tho .. but still i found it difficult i lost 12 marks ! unnecessarily .. havnt started studying fo p3 .. =\
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dont worry bio is the easiest science
ull be fine trust me :)
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but would you say that topics on papers in O/N and M/J 2009 most likely wouldn't come on our papers right? like paper 3 in oct/nov had nitrogen cycle (so complicated..) and genetic engineering, so we won't get those topics in paper 3 right? if they're gonna come anywhere they'll come in paper 1? just trying to use process of elimination........in whatever small way it helps lol :P
you never know
it might!
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definitely u guys will do your best... :) :)
Good Luck
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I've practiced all Bio paper 6 past papers froom 2004, and they've all basically been repetition
Other than 2009...
Last year they got some new topics, which is really freaking me out
Alright everyone, Good Luck
I'm leaving for my exam soon
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I've practiced all Bio paper 6 past papers froom 2004, and they've all basically been repetition
Other than 2009...
Last year they got some new topics, which is really freaking me out
Alright everyone, Good Luck
I'm leaving for my exam soon
good luck with it SEL123.... :) :) :)
do well.. :) :)
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Can someone please explain to me how genetic selection is carried out ?!
My exam's in a few hours and I REALLY NEED IT ! :S
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plz refrain from talking about the exam until 24 hours have passed :)
thank u
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plz refrain from talking about the exam until 24 hours have passed :)
thank u
oh right, I forgot, I'm really sorry
I'll remove it ASAP
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I think 24 hours have passed for bio paper 6 can we disuss now?
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yup:D wat did u guys get for the area of the leaf???
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yup:D wat did u guys get for the area of the leaf???
10.85cm^2
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what about the graph? was it a histogram? a barchart? or a line?
I did a line but everyone is telling me it should be bar or histogram :-\
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10.85cm^2
i got 9.8sumthin well there would be a range i am sure :D
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what about the graph? was it a histogram? a barchart? or a line?
I did a line but everyone is telling me it should be bar or histogram :-\
i made a bar chart
and a histogram i dont think so but i could be corect god noes:P
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what similarity between the teeth of the herm and carn did you write? I couldnt think of any I just wrote they both have points
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hey the 1st q was wat similarity can u c in the two pics related to nutrition .....sumthing like this rite ????
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hey the 1st q was wat similarity can u c in the two pics related to nutrition .....sumthing like this rite ????
Yea it was the first question, what did you write for it?
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it was easy why do you even bother discussing it ???
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Yea it was the first question, what did you write for it?
haha i wrote both have teeth..tht was the only thing related to nutrition in a skull lol :P
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haha i wrote both have teeth..tht was the only thing related to nutrition in a skull lol :P
I wrote they both have molars
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I wrote they both have molars
isnt it sumtin related to teeth rather than wat they asked i.e nutrion...i mean type of teeh is a kind of a very sub topic thing in the nutrition ...but yea it works :D
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hey the 1st q was wat similarity can u c in the two pics related to nutrition .....sumthing like this rite ????
I wrote that both of their teeth are modified according to the food they eat! Im not quite sure if its right though!
Umm what differences did you write for the sheep and dog tooth?
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I wrote that both of their teeth are modified according to the food they eat! Im not quite sure if its right though!
Umm what differences did you write for the sheep and dog tooth?
one has big teeth and one has small teeth...then one has pointed sharp teeth and the others teeth were not pointed......they asked for visible diferences :D
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Bio paper was so STUPID !! ;D ;D .. i felt like i was giving simplified paper3 .. i wonder how will paper 3 be.. n who the hell counts seeds and spines !?! jobless ppl. :P
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i found bio pp6 fine :-X ,but some Qs were pain in the neck >:(
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hey can someone tell me how one recognises a compound that has BOTH ionic and covalent bonds?
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Hey guys, I got a doubt in chem - electrolysis of conc aqueous sodium chloride, wht is the product in the cathode? I think it is hydrogen but the marking scheme in the multiple choice paper O/N 06 says tht it is sodium hydroxide? :S How is tht possible? Thx in advance.. :D
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la2 ...listen
in the cathode it's hydrogen ..in the anode it's chlorine ..and in the bottom of the beaker it is sodium hydroxide ;)
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i got 9.8sumthin well there would be a range i am sure :D
I got 9 :S how do do this question?
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what about the graph? was it a histogram? a barchart? or a line?
I did a line but everyone is telling me it should be bar or histogram :-\
i made a line too!!! :( but i think it was supposed to be a bar graph :(
and also, did we have to have the units as cm^2 for area??? i forgot. but YEAH i put 10.8 too! yay :)
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hey!Im sorry to just barge in like this,
there's a mistake on your drawing! :o
i dont know if you know this, but when it comes to drawing, we should not make like a line above another line.
the lines should be smooth. n yea!they will penalize the mark if drew double line.
i didnt know about this too,until we went through the examiners' report!
hehe... :D
Yes important...no double lines...CIE doesn't appreciate. she's right
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la2 ...listen
in the cathode it's hydrogen ..in the anode it's chlorine ..and in the bottom of the beaker it is sodium hydroxide ;)
ohh k.. thx.. :D
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any important topics for chemistry paper?
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Check the syllabus it has a glossary
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one has big teeth and one has small teeth...then one has pointed sharp teeth and the others teeth were not pointed......they asked for visible diferences :D
Kay, i wrote the same! =P
And what about the penicillin question? I wrote our WBCs accept the antibiotic and begin producing antibodies that inhibit bacterial growth by not letting them form their cell walls. Or something to that effect. Is it right?=/
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yea u get definitions all the time ! every time a different one .. its always there under specific topics .. good thing they give them in the syllabus
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heyyyy;
does anybody know if white 'precipitation' is acceptable for the zinc cation test??? like .. is 'precipitation' acceptable instead of 'precipitate' :S :S :S
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heyyyy;
does anybody know if white 'precipitation' is acceptable for the zinc cation test??? like .. is 'precipitation' acceptable instead of 'precipitate' :S :S :S
Say "white precipitate". Precipitation is a process in forming a precipitate. Like adding silver nitrate (soluble) to sodium chloride (soluble) gives silver chloride (insoluble - precipitate) and sodium nitrate (soluble). Therefore, this reaction is a precipitation reaction but one of the products formed is a precipitate. Get it?
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i have a question ???
can someone please tell me the uses, and dangers of over use of fertilzers pleasee :D:D thank youuu
oh oh anndd the importance of magnesium and nitrates in the soil and what will happen to the plant if the soil lack them. ??? ??? :)
thanx in advance
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i have a question ???
can someone please tell me the uses, and dangers of over use of fertilzers pleasee :D:D thank youuu
oh oh anndd the importance of magnesium and nitrates in the soil and what will happen to the plant if the soil lack them. ??? ??? :)
thanx in advance
Dangers of overuse: Eutrophication
Importance of magnesium: production of chlorophyll - for photosynthesis. Deficiency symptoms: yellow leaves.
Importance of nitrates: makes amino acids, therefore proteins for growth and tissue repair. Deficiency symptoms: short and thin stems, roots etc.
Has this helped?
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Dangers of overuse: Eutrophication
Importance of magnesium: production of chlorophyll - for photosynthesis. Deficiency symptoms: yellow leaves.
Importance of nitrates: makes amino acids, therefore proteins for growth and tissue repair. Deficiency symptoms: short and thin stems, roots etc.
Has this helped?
yes!! thank you so much :D:D
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i need help with chemistry paper 1 M/J 2008 q15 and 19. i know the answer ofc cz i have the ms but i dont understand it so can you explain
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i need help with chemistry paper 1 M/J 2008 q15 and 19. i know the answer ofc cz i have the ms but i dont understand it so can you explain
Q 15 C
not endothermic because rise in temp by 2 *C
neutralisation because acid + base gives salt and water
ZnO + HCl ==> ZnCl2 + H2O
Q 19 D
The process occurring involves the equilibrium between chromate(VI), dichromate(VI) and hydrogen ions
The addition of hydroxide ions causes the concentration of hydrogen ions to decrease, and this brings the equilibrium back to the left-hand side, regenerating yellow chromate(VI) ions. Under alkaline conditions and the orange dichromate(VI) ions predominate in acidic solutions.
Examination of oxidation numbers will show that chromium remains in the +6 oxidation state throughout.
SOURCE : http://www.practicalchemistry.org/experiments/an-equilibrium-involving-chromatevi-and-dichromatevi-ions,284,EX.html
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ok... i want to get one thing clear.. lets say i add some copper sulphate solution in a beaker then i add zinc powder to it. this reaction would be exothermic right? so does it mean that the beaker would be cold when touched?? or would it be hot??? exo-thermic...heat is given out shouldnt the beaker be cold???
and for en-dothermic.. shouldnt the beaker be hot when touched cz heat is taken in
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naah naah...
Ohk...ill clear this.
When it's exo...it gives out heat to the surrounding, which includes the beaker it is in....so it's warmer
When it's endo....it takes in heat from the surrounding, which includes heat from the beaker, this lowers the beaker temp, making it cooler
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yup nid's right .. got it??
adding zinc to copper sulfate is totally different .. its displacement reaction .. its SALT + METAL ---> METAL + SALT
CuSO4(aq) + Zn(s) ---> ZnSO4 + Cu(s)
This reaction is exothermic but ur question tht u;ve asked is different!! (ques 15)
its ACID + BASE ----> SALT + WATER
which is neutralisation and exothermic .. don't wanna confuse u jus keep in mind ACID + BASE ----> SALT + WATER is neutralisation and SALT + METAL ---> METAL + SALT is displacement .. careful not all neutralisation are exothermic .. they usually state the temperature difference in the ques
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ohhh i seee so the beaker is included and heat is taken in or given out to the surroundings. i get itt. thnxx ;)
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yup nid's right .. got it??
adding zinc to copper sulfate is totally different .. its displacement reaction .. its SALT + METAL ---> METAL + SALT
CuSO4(aq) + Zn(s) ---> ZnSO4 + Cu(s)
This reaction is exothermic but ur question tht u;ve asked is different!! (ques 15)
its ACID + BASE ----> SALT + WATER
which is neutralisation and exothermic .. don't wanna confuse u jus keep in mind ACID + BASE ----> SALT + WATER is neutralisation and SALT + METAL ---> METAL + SALT is displacement .. careful not all neutralisation are exothermic .. they usually state the temperature difference in the ques
i know that vin but i just wanted to clear a doubt i had. By the way Thanks for the answer but i get 80% of it. i dint get the part about the chromate thing
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i know that vin but i just wanted to clear a doubt i had. By the way Thanks for the answer but i get 80% of it. i dint get the part about the chromate thing
please someone help with biology artificial and natural selection
it would be really great if someone could prepare some sort of general answer which i could write for selection questions of natural selection and evolution
please also some sort of answer on artificial selection
i have read the book 2 times but just dont seem to get his topic
so please help me and do it as soon as possible only 1 day to go
thankssssss
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yup nid's right .. got it??
adding zinc to copper sulfate is totally different .. its displacement reaction .. its SALT + METAL ---> METAL + SALT
CuSO4(aq) + Zn(s) ---> ZnSO4 + Cu(s)
This reaction is exothermic but ur question tht u;ve asked is different!! (ques 15)
its ACID + BASE ----> SALT + WATER
which is neutralisation and exothermic .. don't wanna confuse u jus keep in mind ACID + BASE ----> SALT + WATER is neutralisation and SALT + METAL ---> METAL + SALT is displacement .. careful not all neutralisation are exothermic .. they usually state the temperature difference in the ques
hey my teacher said tht all neutralisation reactions are exothermic ?????
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Yes all neutralization reactions are exothermic. Heat of neutralization is -57kJ/mol
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i have another question...p1 chem 2006 m/j q19
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i have another question...p1 chem 2006 m/j q19
lol i was just doing it wen i read ur post...:P :o
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lol i was just doing it wen i read ur post...:P :o
and i m confused too....i think it should beA...but ans is c ?????
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lol i wrote A aswell! so do u guys know why the ans is c???
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Hey guys can u help me plz :D
I have two questions here: http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_1.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_1.pdf)
Q)27 and 31, plz explain :)
And 1 question here: http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Nov/0620_w07_qp_1.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Nov/0620_w07_qp_1.pdf)
Q) 11
Thanks in advance :D
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lol i wrote A aswell! so do u guys know why the ans is c???
i m not sure..for me it doesnt really make sense
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lol i wrote A aswell! so do u guys know why the ans is c???
Look, Bariu Chloride is UNSOLUBLE in water, so the method for removing these stuff is filtration. However Barium Sulphate is SOLUBLE in water, so when u are going to filter it it will just pass and not stay as residue. This is why u should straightly crystallize it
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Look, Bariu Chloride is UNSOLUBLE in water, so the method for removing these stuff is filtration. However Barium Sulphate is SOLUBLE in water, so when u are going to filter it it will just pass and not stay as residue. This is why u should straightly crystallize it
i think u read the wrong question... i asked abt m/j 2006 q19
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i think u read the wrong question... i asked abt m/j 2006 q19
hahahahah..hahahah which world is he in lol..
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i think u read the wrong question... i asked abt m/j 2006 q19
hehehe xD
Anyway WTF First of all it should be D, m sure of this its written in my book. How come its C 0.o
By the way can u guys help me with y questions above ;)
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i think u read the wrong question... i asked abt m/j 2006 q19
which sub ?? chem bio
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which sub ?? chem bio
O sh*t lol i fail again :D I think they are talkin about bio :P
By the way Vin help plsss :-* :-* :'( :'(
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its easily C because copper is bellow H in reactivity series but when it in a compound it becomes reactive and able to displace H
and the question says Cu+2 ion wich means it displaced the H and became CuSO4
clear ??
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i cant understand ACIDS,BASES AND SALTS chapter and i am really facing difficulties with it!
if anyone have some goood notes...pls let me know!!
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Hey guys can u help me plz :D
I have two questions here: http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_1.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_1.pdf)
Q)27 and 31, plz explain :)
And 1 question here: http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Nov/0620_w07_qp_1.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Nov/0620_w07_qp_1.pdf)
Q) 11
Thanks in advance :D
Q27 easy .. B
Carbon is more reactive than copper therefore it'll displace Cu to from CO2 and is less reactive and will result in no change
Q31 easy .. B :P
nitrogen oxides .. nitrogen and oxygen are "taken" from the atmosphere rest others are naturally in fuels
2007 Nov
Q11 start start balancing 8 oxygen from A .. always complete combustion of hydro-carbon fuel s give CO2 and H2O .. incomplete give CO and H2O
C5H11OH + 8O2 ---> CO2 + H2O
impossible to balance oxygen!!
C6H9OH + 8O2 ---> cO2 + H2O
try to balance !!
after balancing ..
C6H9OH + 8O2 ---> 6CO2 + 5H2O
ans is B
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vin check ur pm...
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Hey guys can u help me plz :D
I have two questions here: http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_1.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_1.pdf)
Q)27 and 31, plz explain :)
And 1 question here: http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Nov/0620_w07_qp_1.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Nov/0620_w07_qp_1.pdf)
Q) 11
Thanks in advance :D
ANS FOR 11 IS D CAZ 3*CARBON + 2*OXYGEN + 6* HYDROGEN = 74
for 31 it is 1&3..B and i cant explain it..lol...and for 27 it is B cazof the dif in reactivity
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Q27 easy .. B
Carbon is more reactive than copper therefore it'll displace Cu to from CO2 and is less reactive and will result in no change
Q27 easy .. B :P
nitrogen oxides .. nitrogen and oxygen are "taken" from the atmosphere rest others are naturally in fuels
No dude, first they say that all are in fuels, and the question says which are PRODUCTS, so in my book all of them are produced when fossil fuels are burnt
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ANS FOR 11 IS D CAZ 3*CARBON + 2*OXYGEN + 6* HYDROGEN = 74
what are u saying?? ur answer doesnt explain why 8 molecules!! Can u plz clear it ;)?
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Hey guys can u help me plz :D
I have two questions here: http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_1.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_1.pdf)
Q)27 and 31, plz explain :)
And 1 question here: http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Nov/0620_w07_qp_1.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Nov/0620_w07_qp_1.pdf)
Q) 11
Thanks in advance :D
3ashan Q 11 laszim tirsum il compounds , k !
as for question 27 fi nov 06 ......Mg is above carbon fi il reactivity series hence carbon can't displace it , fahamtah?
as for Q 31 .it's C 3ashan , nitrgon oxide is formed when nitrogen reacts with air .....li2ano nitrogen mish maugood fi il fuel .....nitrogen doesn't exist in fuel , right? ..... so that's the reason
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i cant understand ACIDS,BASES AND SALTS chapter and i am really facing difficulties with it!
if anyone have some goood notes...pls let me know!!
I don't have but if u dont understand anything i have time ;) :)
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sulpher and carbon are present in fossil fuel so their oxides have a chance to form
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3ashan Q 11 laszim tirsum il compounds , k !
as for question 27 fi nov 06 ......Mg is above carbon fi il reactivity series hence carbon can't displace it , fahamtah?
as for Q 31 .it's C 3ashan , nitrgon oxide is formed when nitrogen reacts with air .....li2ano nitrogen mish maugood fi il fuel .....nitrogen doesn't exist in fuel , right? ..... so that's the reason
omg i was looking for someone to answer me and then suddenly three people answering xD ;D Thanks i guess i understood bilmasry ;) :P
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omg i was looking for someone to answer me and then suddenly three people answering xD ;D Thanks i guess i understood bilmasry ;) :P
looooooooooool
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Q27 easy .. B
Carbon is more reactive than copper therefore it'll displace Cu to from CO2 and is less reactive and will result in no change
Q27 easy .. B :P
nitrogen oxides .. nitrogen and oxygen are "taken" from the atmosphere rest others are naturally in fuels
2007 Nov
Q11 start start balancing 8 oxygen from A .. always complete combustion of hydro-carbon fuel s give CO2 and H2O .. incomplete give CO and H2O
C5H11OH + 8O2 ---> CO2 + H2O
impossible to balance oxygen!!
C6H9OH + 8O2 ---> cO2 + H2O
try to balance !!
after balancing ..
C6H9OH + 8O2 ---> 6CO2 + 5H2O
ans is B
thx for the detailed explaination :D
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what are u saying?? ur answer doesnt explain why 8 molecules!! Can u plz clear it ;)?
opas sry i ans q 10..q11..wait
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i have another question...p1 chem 2006 m/j q19
ans is C for sure ..
try to write an equation for each ..
Cu + H2SO4 ----> not possible as Cu is less reactive so cannot displace H2 therefore Cu as a metal is present and no ions
Cu(OH)2 + H2SO4 ---> CuSO4 + H2O
this is a neutralisation reaction .. so salt and water are formed .. here Cu+2 are present Cu+2SO4-2 = CuSO4
CuCO3 + H2SO4 ---> CuSO4 + H2O + CO2
again salt Cu+2SO4-2 = CuSO4
so check 2 and 3 so the ans is C
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opas sry i ans q 10..q11..wait
already answered no worries !! ;) ;)
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O sh*t lol i fail again :D I think they are talkin about bio :P
By the way Vin help plsss :-* :-* :'( :'(
:-* :-* ?? WTF ?? :P
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Exactly xD :D ;D
Guys okay all thanks i understand all questions xD
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ans is C for sure ..
try to write an equation for each ..
Cu + H2SO4 ----> not possible as Cu is less reactive so cannot displace H2 therefore Cu as a metal is present and no ions
Cu(OH)2 + H2SO4 ---> CuSO4 + H2O
this is a neutralisation reaction .. so salt and water are formed .. here Cu+2 are present Cu+2SO4-2 = CuSO4
CuCO3 + H2SO4 ---> CuSO4 + H2O + CO2
again salt Cu+2SO4-2 = CuSO4
so check 2 and 3 so the ans is C
Thanks
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i have my biology paper 3 on monday...thts 2 days frm now...any ideas on how to ace it...i aced the paper 6...and i wanna do the same to paper 3 :P any tips of some sort...?
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i have my biology paper 3 on monday...thts 2 days frm now...any ideas on how to ace it...i aced the paper 6...and i wanna do the same to paper 3 :P any tips of some sort...?
aced paper 6 .. paper 3 wont be tht a prob ;) this time paper 6 was literally lik p3 or thts wat i felt .. study ur notes/guide if u hav/ textbook .. know everything from the syllabus and dont miss out the smallest thing for it ;) best of luck !! which country ??
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Study the whole book, solve a couple of past papers and check the ones u had doubt on b4. Study tests, nutrition, Ecology (food pyramids and stuff) and geneatics(mitosis, XY, Malaria, genatic sh*t) ofc study everything but these are the stuff i remember that are very important ;)
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We're all screwed for Bio P3. VERY BADLY. :(
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We're all screwed for Bio P3. VERY BADLY. :(
y do u think soo???
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We're all screwed for Bio P3. VERY BADLY. :(
HHAHAAH Just like Gymnan's signiture xD
-
y do u think soo???
Umm, maybe because...
THERE ARE ONLY TWO DAYS LEFT AND I HAVE YET TO START THE SYLLABUS.
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aced paper 6 .. paper 3 wont be tht a prob ;) this time paper 6 was literally lik p3 or thts wat i felt .. study ur notes/guide if u hav/ textbook .. know everything from the syllabus and dont miss out the smallest thing for it ;) best of luck !! which country ??
IM FROM PAKISTAAANN BEEATCH!!! :P...but i live in the dubai...
you...?
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IM FROM PAKISTAAANN BEEATCH!!! :P...but i live in the dubai...
you...?
Paki. Riyadh, KSA. :P
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Umm, maybe because...
THERE ARE ONLY TWO DAYS LEFT AND I HAVE YET TO START THE SYLLABUS.
hah then yea u r..:P
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No, I'm not screwed. :P Just have to revise it all again. :/
Oh well, Best of Luck! :)
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Umm, maybe because...
THERE ARE ONLY TWO DAYS LEFT AND I HAVE YET TO START THE SYLLABUS.
hmm... I never looked in the syllabus 0.0 I know its wrong but screw that i only knew its important very late. I always just studied from three diff books and took all the important sh*t xD ;D
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guys can someone tell me exactly what to write if a questions come about the nitrogen cycle
i dont understand, which kinds of bacteria do what like which one makes the N2 to ammonia and than the ammonia to nitrates etc. which kind is rhizobium?
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guys can someone tell me exactly what to write if a questions come about the nitrogen cycle
i dont understand, which kinds of bacteria do what like which one makes the N2 to ammonia and than the ammonia to nitrates etc. which kind is rhizobium?
Nitrogen Fixing Bacteria change N2 (nitrogen in air) to to Ammonium. They are found in root nodules of leguminous plants (for example: peas and beans)
Then the Nitrifying Bacteria takes that ammonium and converts it to Nitrites and Nitrates.
Decomposers decompose dead organisms and wastes to ammonium.
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WHY IS
S + 02 --> S02
2S02 + 02-->2 S03
SO3 + H20--> H2SO4
WHICH 1 ARE REDOX ? AND WHY IS THE ONE NOT A REDOX NOT A REDOX
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You stated the contact process
i hope so :)
S + 02 --> S02 is when suphur burns in air. it is not redox
2S02 + 02--> Is by use air + catalyst + and high temp , don't really no if its redox,
S03 +H20 --> H2S04 is the last process in making sulphuric acid, by adding water to sulphur trioxide.
Kimo tell me the solution.
Can someone explain single cell protien. ??? ???
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You stated the contact process
i hope so :)
S + 02 --> S02 is when suphur burns in air. it is not redox
2S02 + 02--> Is by use air + catalyst + and high temp , don't really no if its redox,
S03 +H20 --> H2S04 is the last process in making sulphuric acid, by adding water to sulphur trioxide.
Kimo tell me the solution.
Can someone explain single cell protien. ??? ???
lol its in summer 2007 q 16 paper 1
1 and 2 are redox :/ why?
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both are oxidation reactions !!!
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both are oxidation reactions !!!
LOOK AT THE MARK scheme!
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LOOK AT THE MARK scheme!
r u talking abt jun 2007 q 16 paper 1 ??
wats wrong with u man ??
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Heyyy, I need some help in Bio...
1) Regarding the kidneys, what's the difference between the first renal tubule and the second? What is the Loop of Henle? And what is the function of these parts?
2) In transpiration, can someone please explain root pressure, capillary action and transpiration stream?
Thanks in advance
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r u talking abt jun 2007 q 16 paper 1 ??
wats wrong with u man ??
sorry man ..im jst tensed up :(
really sorry .im wasting alot of time and stuff ! :-\ :-X :-[
thanks anyway!
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r u talking abt jun 2007 q 16 paper 1 ??
wats wrong with u man ??
Hey dude, you're looking at the wrong mark scheme, you're looking at the Biology one!
So the answer to Q16 is C, but can anyone explain why?
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Hey dude, you're looking at the wrong mark scheme, you're looking at the Biology one!
So the answer to Q16 is C, but can anyone explain why?
haha LOL wat a coincidence :P .. sorry guys i guess im stressed out !! :-\ :-\ :( :( wait lemme see .. :-\
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You stated the contact process
i hope so :)
S + 02 --> S02 is when suphur burns in air. it is not redox
2S02 + 02--> Is by use air + catalyst + and high temp , don't really no if its redox,
S03 +H20 --> H2S04 is the last process in making sulphuric acid, by adding water to sulphur trioxide.
Kimo tell me the solution.
Can someone explain single cell protien. ??? ???
Incorrect. SO3 is not placed in water as the direction is too violent, it is placed in Sulphuric Acid instead to make Oleum, it is then diluted with water to form Sulphuric acid.
The three conditions required for the Contact Process are : 450 degree celsius, Vanadium (V) Oxide catalyst and the reaction occurs at atmospheric pressure.
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Heyy guys please can anyone of u please answer the questions I asked earlier?
They're kinda freakin me out! :(
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Heyyy, I need some help in Bio...
1) Regarding the kidneys, what's the difference between the first renal tubule and the second? What is the Loop of Henle? And what is the function of these parts?
2) In transpiration, can someone please explain root pressure, capillary action and transpiration stream?
Thanks in advance
I've posted this earlier...wait hold on
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Incorrect. SO3 is not placed in water as the direction is too violent, it is placed in Sulphuric Acid instead to make Oleum, it is then diluted with water to form Sulphuric acid.
The three conditions required for the Contact Process are : 450 degree celsius, Vanadium (V) Oxide catalyst and the reaction occurs at atmospheric pressure.
this is not teh issue
teh isue is which one of them is redox???? the snwer is 1 and 2
whyyyyyyyyyyyyyyyyyyyyy?
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Blood is got to the kidney via renal artery. The renal artery divides into a great number of arterioles and capillaries, mostly in the cortex. Each arteriole leads to a glomerulus. The pressure in the glomerulus causes part of the blood plasma to leak the capillary walls. The RBC's and proteins in plasma r too big to pass out. The fluid that moves out contains mainly water with dissolved salts, urea, glucose and uric acid. The process by which the fluid is filtered out of the blood by the glomerulus is called ultrafiltration. The filtrate from the glomeruls collects in the renal capsule and trickles down the renal tubule. As it does so, the capillaries which surround it absorb the substance the body needs. All the glucose is absorbed, with much of the water(depends on the state of hydration). The some salts r taken back to keep the correct con in the blood. This process of taking back the required substances is called selective reabsorption.
Substances that r not needed pass further down to the collecting duct into the pelvis of the kidney. From here the fluid, now called urine, passes down the ureter to the bladder.
Nephron- A single glomerulus with its renal artery, renal tubule and blood capillaries
visit the site for a good animation http://www.biologymad.com/resources/kidney.swf
I'll get the transpiration stuff in a while
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Heyyy, I need some help in Bio...
1) Regarding the kidneys, what's the difference between the first renal tubule and the second? What is the Loop of Henle? And what is the function of these parts?
2) In transpiration, can someone please explain root pressure, capillary action and transpiration stream?
Thanks in advance
1. The first renal tubule is when the bloody gets filtered through the glomerulus into the Bowman's capsule or the renal capsule. The plasma leak the walls of the glomerulus but the proteins and RBCs are too big to pass out so they go into the renal capsule then they pass into the renal tubule which is the Loop of Henle where salt and water is reabsorbed according to the body's needs.
2. Root pressure: The roots is constantly absorbing water from the soil by osmosis so the cells in the root are highly turgid. This turgor pressure is what forces the water to move up the plant (from the root to the shoot etc)
Transpiration force: The leaves are constantly transpiring (during the daylight). As the leaves lose water through the stomata the water potential in the leaves is lower than the rest of the plant. SO osmosis basically happens because the water from the roots from upwards due to the water potential gradient since the roots have a higher water potential that inside the leaves.
Capillary action is basically when water gets distributed to the plant via the xylem.
I hope that made sense!
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If you want more resources on transport in plants...here's the thread
https://studentforums.biz/index.php/topic,763.0.html (https://studentforums.biz/index.php/topic,763.0.html)
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hey you all missed my mind up
What is REDOX to you
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A reaction in which oxidation and reduction happen simultaneously
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this is not teh issue
teh isue is which one of them is redox???? the snwer is 1 and 2
whyyyyyyyyyyyyyyyyyyyyy?
Redox reactions, or oxidation-reduction reactions, have a number of similarities to acid-base reactions. Redox reactions are concerned with the transfer of electrons between species. Like acid-base reactions, redox reactions are a matched set -- you don't have an oxidation reaction without a reduction reaction happening at the same time. Oxidation refers to the loss of electrons, while reduction refers to the gain of electrons.
OIL RIG
oxidation is loss of electrons
reduction is the gain of electrons
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ok then
oxidation is
gain of oxygen
loss of electron
loss of hydrogen
in the first two choices the sulfer molecules are gaining Oxygen
and clearly there is no e) 1and 2 and 3
so its C) 1 and two
think rationally
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nid 404 and K_M, thanks a gazillion guys! =D
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You got it wrong
Remember OILRIG
Oxidation
Is
Loss (of electrons)
Reduction
Is
Gain (of electron
put the question up
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heeeeeeeeeey
the question is easy
i think you should study bio
wich i have question in
what are the keywords in transpiration (6 marks)
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You got it wrong
Remember OILRIG
Oxidation
Is
Loss (of electrons)
Reduction
Is
Gain (of electron
put the question up
Here is the question about redox reactions. The answer is C, but I dunno why. I know about OIL RIG, but still don't get it. Surely 1 and 2 is only oxidation reaction, not redox.
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A reaction in which oxidation and reduction happen simultaneously
I LOVE YOU VIN !!!!!!!!!! <3 + REP!
that bold part saved my mind !!!!!!!!
and yeh good point soraam
but just a question...The H20 GAINS OXYGEN FORM SO4 isnt that oxidation too :-X
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loooook the sulpher is oxidised the oxygen is reduced
if something is oxidised then the other is reduced so REDOX
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no that synthesis reaction
-
it gained oxygen and hydrogen oxidation and reduction to the same compound
its like 1-1=0 so no oxidation then no REDOX
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loooook the sulpher is oxidised the oxygen is reduced
if something is oxidised then the other is reduced so REDOX
OOOOOOOOOOOOOOOOH OOOOOOOOOOK THANKS !
to the same compound !!
i see
cheers mate
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it gained oxygen and hydrogen oxidation and reduction to the same compound
its like 1-1=0 so no oxidation then no REDOX
How do you mean, I still don't get why 3 is not redox. Surely SO3 is reduced, H20 is oxidised?
And for 1 and 2,
S is being oxidised, O2 is being reduced
SO2 is being oxidised, O2 is being reduced right?
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so will someone tell me whats single cell protien ??? ???
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no SO3 gaines O and H
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it gained oxygen and hydrogen oxidation and reduction to the same compound
its like 1-1=0 so no oxidation then no REDOX
some1 who does AS CHEM step in plz
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Redox reactions, or oxidation-reduction reactions, have a number of similarities to acid-base reactions. Redox reactions are concerned with the transfer of electrons between species. Like acid-base reactions, redox reactions are a matched set -- you don't have an oxidation reaction without a reduction reaction happening at the same time. Oxidation refers to the loss of electrons, while reduction refers to the gain of electrons.
OIL RIG
oxidation is loss of electrons
reduction is the gain of electrons
Not only that, oxidation can also be referred to an increase in the oxidation number and the gain of oxygen.
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no SO3 gaines O and H
But if SO3 have been oxidised because they gain H2 and O, then surely H2O is being reduced, so redox
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Not only that, oxidation can also be referred to an increase in the oxidation number and the gain of oxygen.
So is it true that if there is an oxidation reaction, there must also be a reduction reaction at the same time?
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so will someone tell me whats single cell protien ??? ???
Single cell protein typically refers to sources of mixed protein extracted from pure or mixed cultures of algae, yeasts, fungi or bacteria used as a substitute for protein-rich foods, in human and animal feeds.
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SO3 is oxidised and reduced
thats not what happens but you cam imagin it this way
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Single cell protein is produced by microorganisms such as bacteria, fungi and unicellular algae in a fermentation vessel. While the product contains 72% protein, it does not taste very nice and is expensive to produce.
An alternative is Quorn. The filamentous fungus Fusarium graninearum is used to produce the mycoprotein known as Quorn.
The fungus is grown in a medium containing glucose and mineral salts at 30 degrees in the fermenter. The fungus is filtered off at a steady rate and dried. The filamentous nature of the fungus gives it a texture similar to meat. It can be flavoured with natural products and cooked i na similar way to meat. It is rich in protein, low in fat and has a good level fo fibre.
I won't worry about it much if I were you. Hope I could help!
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this drove me crazy during my IGCSEs too..
S + 02 --> S02
S - oxidation number 0..
O2 - oxidation number 0
SO2 --> oxidation number of O = (-2*2) = -4 , thus oxidation number of S = +4
S--> 0 to 4 oxidation
O -> 0 to -4 reduction
thus redox.
2S02 + 02-->2 S03
2SO2 -> oxidation number of O = (-2*2) = -4, thus S = +4. O2 -> 0, final of O = -4+0 = -4
SO3--> Oxidation number of O = (-2*3) = -6, of S = +6
Final , S --> 4 to 6 oxidation
O --> -4 to -6 reduction
SO3 + H20--> H2SO4
SO3 --> O = (-3*2) = -6 , thus S = +6
H2O --> O = -2, thus H = +2
O in both compounds thus, final number of O = -6-2 = -8
H2SO4--> O = (-2*4) = -8, thus H = +2, as final oxidation number of the compound shud be 0, -8+2+S = 0
thus, S = +6
now the changes
S --> 6 to 6
H --> 2 to 2
O --> -8 to -8..
NOt redox.
I AM NOT SURE ABOUT THIS , NID PLZ CHECK!
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do any one know any memonics for chemstry?
-
I dont quite understand what the question is saying ; What RESULT ?
-
Is the answer D?
-
I dont quite understand what the question is saying ; What RESULT ?
i think its B
-
I dont quite understand what the question is saying ; What RESULT ?
woah i dont get that either
and whats the difference between nitrite and nitrates, do plants take in both kinds?
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Is the answer D?
YES !!! But how ?
NH3 and N2 wont react by themselves.... they need a catalyst, right ?
-
YES !!! But how ?
NH3 and H2 wont react by themselves.... they need a catalyst, right ?
Where did H2 come from? O_O...how'd u get it nid404?
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YES !!! But how ?
NH3 and N2 wont react by themselves.... they need a catalyst, right ?
exactly! thts wat i thought !!
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exactly! thts wat i thought !!
Lets w8 for Nid. :)
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is answer d?
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YES !!! But how ?
NH3 and N2 wont react by themselves.... they need a catalyst, right ?
naah naah...you don't get the question...you know the whole tube is filled with the 2 gases. then it's immersed in water. ammonia dissolves in water, this makes the water rise up....because some of the gas has dissolved..water takes up the empty space
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Thanks Nid :)
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oct nov 2009 question no 17,18,21,34
explain me fast urgently
??? ??? ??? ??? ??? ??? ??? ??? ??? ???
in paper 1
-
I've got a small question:
Blood in the smallest arteries in a muscle flows into networks of capillaries.
The flow through these networks is much slower than through arteries or veins.
Suggest how these features, together with the structure of capillaries, assist in supplying glucose to muscle cells.
(4 marks)
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naah naah...you don't get the question...you know the whole tube is filled with the 2 gases. then it's immersed in water. ammonia dissolves in water, this makes the water rise up....because some of the gas has dissolved..water takes up the empty space
oh ok .. umm .. y not C .. even it has ammonia .. :-\ or is that without any other insoluble gas water wont move up due to pressure or something ?(i kno i sound stupid :|)
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Thanks Nid :)
hey not a problem :)
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oct nov 2009 question no 17,18,21,34
explain me fast urgently
??? ??? ??? ??? ??? ??? ??? ??? ??? ???
chem / bio ??
-
oh ok .. umm .. y not C .. even it has ammonia .. :-\ or is that without any other insoluble gas water wont move up due to pressure or something ?(i kno i sound stupid :|)
That is a GOOD question.
-
chemistry
-
oh ok .. umm .. y not C .. even it has ammonia .. :-\ or is that without any other insoluble gas water wont move up due to pressure or something ?(i kno i sound stupid :|)
if it were ammonia, the whole thing wudve dissolved and there wudve been no gas left in it...bu the RESULT shows that there was some gas in the tube..
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chemistry
variant?
-
11
-
I've got a small question:
Blood in the smallest arteries in a muscle flows into networks of capillaries.
The flow through these networks is much slower than through arteries or veins.
Suggest how these features, together with the structure of capillaries, assist in supplying glucose to muscle cells.
(4 marks)
thin in diameter/small, glucose supplied faster
slow rate so more amount of glucose supplied
capillaries are numerous, have large surface area
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??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ???
oct nov 2009 question no 17,18,21,34
-
??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ???
oct nov 2009 question no 17,18,21,34
Please do not SPAM with multiple question marks.
A@di will be along soon - just hang in there. ;)
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thin in diameter/small, glucose supplied faster
slow rate so more amount of glucose supplied
capillaries are numerous, have large surface area
also, blood cells pass through the capillaries slowly to allow diffusion of materials and the tissue fliud
capillaries are smaller and thin so diffusion rate is faster
tissue fluid provides a medium of exchange between the capillaries and the surrounding muscle cells
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variant?
variant?
17) coppe sulfate is hydrated, wen it loses water, water can again be added to make it blue. so reversible. C
18) D - Carbon monoxide reduces Iron oxide. (Iron extraction, remember?)
21) D= to be alkaline ph>7, R and S
24) A = the color gets darker down the halogens group, Thus Astatine is either dark brown or black, cant be dark brown, because the row also says its gas. Astatine is solid as its the last in the group of halogens..
34) A - 78.09% nitrogen, 20.95% oxygen,0.038% carbon dioxide,
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oct nov 2009 question no 17,18,21,34
explain me fast urgently
??? ??? ??? ??? ??? ??? ??? ??? ??? ???
in paper 1
21. D anything greater than 7 is alkaline
34. A
Earth's composition of air
Nitrogen : 78%
Oxygen : 21%
CO2 : 0.04%
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thanxs
-
if it were ammonia, the whole thing wudve dissolved and there wudve been no gas left in it...bu the RESULT shows that there was some gas in the tube..
plz tell me if this was clear or not?
-
plz tell me if this was clear or not?
oh ya ya thanks !! :D
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thin in diameter/small, glucose supplied faster
slow rate so more amount of glucose supplied
capillaries are numerous, have large surface area
Thanks!!
-
Thanks!!
finally u solved the prob of quoting :P :)
-
have a question:
In which change is the nitrogen reduced?
A. NH3 to NO
B.NH3 to NO-3
C.N2 to NH3
D. N3- to N2
PLLZZ HELLP OOUUTT!!
i have NO idea of how to do this question!
-
???
I have a small doubt, i think i misunderstood the concept or this is an exception but can someone please clear it for me!
Active uptake is the movement of molecules of a substance from low concentration to high concentration against the concentration gradient. Then how is mineral ions absorbed by the roots of a plant? Doesnt the soil have a higher concentration of mineral ions than the plants?
-
have a question:
In which change is the nitrogen reduced?
A. NH3 to NO
B.NH3 to NO-3
C.N2 to NH3
D. N3- to N2
PLLZZ HELLP OOUUTT!!
i have NO idea of how to do this question!
-
have a question:
In which change is the nitrogen reduced?
A. NH3 to NO
B.NH3 to NO-3
C.N2 to NH3
D. N3- to N2
PLLZZ HELLP OOUUTT!!
i have NO idea of how to do this question!
it should be 'D' .. check the ans n tell .. i'll giv u an explanation if its right ..
-
???
I have a small doubt, i think i misunderstood the concept or this is an exception but can someone please clear it for me!
Active uptake is the movement of molecules of a substance from low concentration to high concentration against the concentration gradient. Then how is mineral ions absorbed by the roots of a plant? Doesnt the soil have a higher concentration of mineral ions than the plants?
I answered that in the other thread (IGCSE BIOLOGY------>TRANSPORT IN PLANTS)...didn't u read it? Or do I suck at explaining stuff? ;D LOL
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http://www.freeexampapers.us/IGCSE/Biology/CIE/2006%20Nov/0610_w06_qp_3.pdf (http://www.freeexampapers.us/IGCSE/Biology/CIE/2006%20Nov/0610_w06_qp_3.pdf)
6)a) Both ovums... can u make a small drawing or smth :) Thanks :D
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it should be 'D' .. check the ans n tell .. i'll giv u an explanation if its right ..
nope, its C.
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I answered that in the other thread (IGCSE BIOLOGY------>TRANSPORT IN PLANTS)...didn't u read it? Or do I suck at explaining stuff? ;D LOL
oh crap i didnt see it! thanks will check it now!
-
Can someone explain why it's C i thought it's D
-
http://www.freeexampapers.us/IGCSE/Biology/CIE/2006%20Nov/0610_w06_qp_3.pdf (http://www.freeexampapers.us/IGCSE/Biology/CIE/2006%20Nov/0610_w06_qp_3.pdf)
6)a) Both ovums... can u make a small drawing or smth :) Thanks :D
here ..
-
can any1 explain wata a negative feedback wid sum defination thnaku :)
-
here ..
Thx man u look like u studied this chapter very well ;) ;D jk xD
-
have a question:
In which change is the nitrogen reduced?
A. NH3 to NO
B.NH3 to NO-3
C.N2 to NH3
D. N3- to N2
PLLZZ HELLP OOUUTT!!
i have NO idea of how to do this question!
C. ox state of N2 gas is always 0. it goes from 0 to -3 in NH3
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C. ox state of N2 gas is always 0. it goes from 0 to -3 in NH3
hey can u explain this?
how does one know the oxidation state and how its change is calculated
-
I really don't think its oxidation state has changed to -3 here. It hasn't exacly gained 3 electrons. Ammonia is a covalent compound.
THe reason this question is tough is that there are 3 definitions of reduction.
1) Gain of electrons
2) Loss of oxygen
3) Gain of hydrogen (No oxygen must be involved)
As far your question is concerned, it is reduction since the N2 has gained hydrogen to form NH3.
Please correct me if I am wrong...
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H - Oxidation number : 1
O - Oxidation number : -2
N - Oxidation number : -3
In A and B, as Nitrogen forms a covalent bond with Hydrogen (Ammonia) and Oxygen (Nitrate, Nitrogen Oxide), the oxidation number will remain as -3.
In C, we know that the valency of Nitrogen molecule is zero, and we know that when Nitrogen forms a covalent bond with Hydrogen (Ammonia), the oxidation number will be -3, since its oxidation number has decreased, we can tell that a reduction has taken place.
In D, we know that the valency of Nitrogen molecule is zero, and we know that when Nitrogen forms a covalent bond with Hydrogen (Ammonia), the oxidation number will be -3, since its oxidation number has increased, we can tell that a oxidation has taken place.
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can any1 explain wata a negative feedback wid sum defination thnaku :)
Heyy.. see all the time the hypothalamus is monitoring small changes in the temperature of the blood. Like if it rises above normal, then it places actions to lower it. Then, as soon as the hypothalamus senses the lowered temperature, it stops these actions from taking place and starts off another action to help raise the temperature of the blood. This is known as Negative feedback.
The "feedback" refers to the fact tht when the hypothalamus has made the skin take actions to increase heat loss, information abt the effects of these action are FED BACK to the hypothalamus, as it senses the drop in blood temperature.
The "Negative" is because the information that the blood has cooled stops the hypothalamus making the skin do thses things..
I hope u have understood.. ;D
-
Heyy guys.. can someone explain wht happens during the process of blood clotting? :S because different books say different things and im confused.. :S Thx in advance... :D
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The evolution of high-pressure blood circulation in vertebrates has brought with it the risk of bleeding after injury to tissues. Mechanisms to prevent bleeding (i.e., hemostatic mechanisms) are essential to maintain the closed blood-circulatory system. Normal homeostasis is the responsibility of a complex system of three individual components: blood cells (platelets), cells that line the blood vessels (endothelial cells), and blood proteins (blood-clotting proteins). The blood platelet is a no nucleated cell that circulates in the blood in an inactive, resting form. Endothelial cells line the wall of the blood vessel and inhibit blood from clotting on the vessel wall under normal conditions. Blood-clotting proteins circulate in the blood plasma in an inactive form, poised to participate in blood coagulation upon tissue injury. Blood-clotting proteins generate thrombin, an enzyme that converts fibrinogen to fibrin, and a reaction that leads to the formation of a fibrin clot.
-
The evolution of high-pressure blood circulation in vertebrates has brought with it the risk of bleeding after injury to tissues. Mechanisms to prevent bleeding (i.e., hemostatic mechanisms) are essential to maintain the closed blood-circulatory system. Normal homeostasis is the responsibility of a complex system of three individual components: blood cells (platelets), cells that line the blood vessels (endothelial cells), and blood proteins (blood-clotting proteins). The blood platelet is a no nucleated cell that circulates in the blood in an inactive, resting form. Endothelial cells line the wall of the blood vessel and inhibit blood from clotting on the vessel wall under normal conditions. Blood-clotting proteins circulate in the blood plasma in an inactive form, poised to participate in blood coagulation upon tissue injury. Blood-clotting proteins generate thrombin, an enzyme that converts fibrinogen to fibrin, and a reaction that leads to the formation of a fibrin clot.
Thanks a lot!! :D
-
blood clotting---
usully the inner walls of the blood vessels have a "smooth' lining and when the are cut, they get a jagged lining. when the platelets touch this, 2 things happen--
1)they release thrombin which sets off a chain of reactions turning fibronogen into fibrin forming a mesh od fibres trapping RBCs.
2)they stick to each other at the wound to cover it up.
-
blood clotting---
usully the inner walls of the blood vessels have a "smooth' lining and when the are cut, they get a jagged lining. when the platelets touch this, 2 things happen--
1)they release thrombin which sets off a chain of reactions turning fibronogen into fibrin forming a mesh od fibres trapping RBCs.
2)they stick to each other at the wound to cover it up.
Thanks.. :D and do v need to know the elements of the xylem and phloem (like tracheids, vessels, parenchyma) for the exam? :S
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i have always hoped to pass AT LEAST ONE chemistry exam :( :( :-[ :-[ :-[ :-[ :-[ (((( WHAT TO DOO ))))
-
i have always hoped to pass AT LEAST ONE chemistry exam :( :( :-[ :-[ :-[ :-[ :-[ (((( WHAT TO DOO ))))
Do past papers - its your only hope. :)
AND READ the textbook.
-
Thanks.. :D and do v need to know the elements of the xylem and phloem (like tracheids, vessels, parenchyma) for the exam? :S
im not sure, lemme check the syllabus and tell you :)
-
no i just checked, u only need 2 noe the positions of the xylem nd phloem nd cortex (xylems always inside) :)
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no i just checked, u only need 2 noe the positions of the xylem nd phloem nd cortex (xylems always inside) :)
Oh k.. thx!! :D
-
nytime ;)
-
Heyy.. see all the time the hypothalamus is monitoring small changes in the temperature of the blood. Like if it rises above normal, then it places actions to lower it. Then, as soon as the hypothalamus senses the lowered temperature, it stops these actions from taking place and starts off another action to help raise the temperature of the blood. This is known as Negative feedback.
The "feedback" refers to the fact tht when the hypothalamus has made the skin take actions to increase heat loss, information abt the effects of these action are FED BACK to the hypothalamus, as it senses the drop in blood temperature.
The "Negative" is because the information that the blood has cooled stops the hypothalamus making the skin do thses things..
I hope u have understood.. ;D
So you can get a negative feedback in many ways besides blood monitoring,
you can get negative geotropism and phototropism or negative phototaxis.
Thanks for ur explanation.
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So you can get a negative feedback in many ways besides blood monitoring,
you can get negative geotropism and phototropism or negative phototaxis.
Thanks for ur explanation.
Np.. :D And i dont think Negative feedback implys to plant, Negative geotropism is when a plant's shoot grows away from gravity or in the opposite direction from the gravity. This is due to auxins (plant growth hormone).. :)
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can any 1 tell me tips for paper 1 in chemistry
-
can any 1 tell me tips for paper 1 in chemistry
Past papers!! Lots of them! :D
-
Many bacterial diseases can no longer be treated with antibiotics. Outline how
antibiotic-resistant strains of bacteria can develop. ??? ??? Why cant they.
Antibiotics can kill bacteria without harming living cells, so whats makes
it hard for antibiotics to kill bacteria, if someone can give a further explanation. :-\
-
Past papers!! Lots of them! :D
ya do as much past papers as u can ;) ..........i hope u kill the paper 8)
-
thanx
-
Many bacterial diseases can no longer be treated with antibiotics. Outline how
antibiotic-resistant strains of bacteria can develop. ??? ??? Why cant they.
Antibiotics can kill bacteria without harming living cells, so whats makes
it hard for antibiotics to kill bacteria, if someone can give a further explanation. :-\
Well, antibiotics are selective. They are meant to destroy a specific bacteria. If a mutation happens to some of these bacteria, then the antibiotic will destroy ONLY the bacteria that did not get mutated. And the bacteria that got mutated will reproduce and the antibiotic will no longer be effective.. :) I think thare is more to it but hope this helps.. :D
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i have a q...c sumtimes they give a microscopic veiw of a leaf and tell us to i dentify phloem and xylem...how do we no which one is which...i remember my teacher sayin sumthin abt it relating to color and size....can ane one explain..Thanks :D
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xylems always on the inside :)
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What topics do we think will come on Bio Paper 3 tomorrow?
I guess genetic engineering won't come since it came in O/N last year, and teeth can't come, since we had SO MUCH of that in P6 (variant 2, at least). Penicillin came in P6 too... so what else is left for Paper 3? Any ideas?
Reproduction - both in plants and animal (BIG chap)
Environment n stuff .. definitions of ecosystems population
Genetic variation .. mitosis and meiosis
Transport in animals and plants ..
Enzymes
wat else ?? .. i'll tell if i can think of any ..
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i have a q...c sumtimes they give a microscopic veiw of a leaf and tell us to i dentify phloem and xylem...how do we no which one is which...i remember my teacher sayin sumthin abt it relating to color and size....can ane one explain..Thanks :D
u want other labels too ??
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Hey guys, i got two questions:
1) Outline the use of microorganisms and
fermenters to manufacture the antibiotic
penicillin
2) The role of the fungus Penicillium in
the production of antibiotic penicillin.
:S its in the syllabus and im clueless abt them!! Thx!! ;D
-
Hey guys, i got two questions:
1) Outline the use of microorganisms and
fermenters to manufacture the antibiotic
penicillin
2) The role of the fungus Penicillium in
the production of antibiotic penicillin.
:S its in the syllabus and im clueless abt them!! Thx!! ;D
search in this topic .. this has been discussed earlier ..
-
search in this topic .. this has been discussed earlier ..
Ohh k.. my bad.. :P
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hey can1 explain wats a negative feedback
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xylems always on the inside :)
Xylem is always on the inside when it's a transverse section of a root or stem,
But i think when it comes to the microscopic view of a leaf it's different
-
Looks like ~VIN1094~ did his job ;D already
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hey can1 explain wats a negative feedback
Heyy.. see all the time the hypothalamus is monitoring small changes in the temperature of the blood. Like if it rises above normal, then it places actions to lower it. Then, as soon as the hypothalamus senses the lowered temperature, it stops these actions from taking place and starts off another action to help raise the temperature of the blood. This is known as Negative feedback.
The "feedback" refers to the fact tht when the hypothalamus has made the skin take actions to increase heat loss, information abt the effects of these action are FED BACK to the hypothalamus, as it senses the drop in blood temperature.
The "Negative" is because the information that the blood has cooled stops the hypothalamus making the skin do thses things..
I hope u have understood.. ;D
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What topics do we think will come on Bio Paper 3 tomorrow?
I guess genetic engineering won't come since it came in O/N last year, and teeth can't come, since we had SO MUCH of that in P6 (variant 2, at least). Penicillin came in P6 too... so what else is left for Paper 3? Any ideas?
Reproduction - both in plants and animal (BIG chap)
Environment n stuff .. definitions of ecosystems population
Genetic variation .. mitosis and meiosis
Transport in animals and plants ..
Enzymes
wat else ?? .. i'll tell if i can think of any ..
there also huge chances for homeostasis and excretion
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there also huge chances for homeostasis and excretion
they can also ask about the heart, artery and veins + fungi and bacteria
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What topics do we think will come on Bio Paper 3 tomorrow?
I guess genetic engineering won't come since it came in O/N last year, and teeth can't come, since we had SO MUCH of that in P6 (variant 2, at least). Penicillin came in P6 too... so what else is left for Paper 3? Any ideas?
they can ask the same stuff again...for example, nov 2009 no. 6c and may 2009 no. 2e are the same questions!
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yea u cannot trust them .. anything might turn up .. its better u know everything ... :)
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yea u cannot trust them .. anything might turn up .. its better u know everything ...
yea CIE is pretty evil >:(
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the weird thing is most of the ppl who take exams 4rom cie hate it,,including me!!
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i've got a question here:
State the characteristic which is described in each of the following statements about living things.
Statement: The increase in size or number of cells of an organism.
Characterstic: ???
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the weird thing is most of the ppl who take exams 4rom cie hate it,,including me!!
got no other option here...
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growth??
gd luck then wid igs ;)
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i've got a question here:
State the characteristic which is described in each of the following statements about living things.
Statement: The increase in size or number of cells of an organism.
Characterstic: ???
growth
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yea u cannot trust them .. anything might turn up .. its better u know everything ... :)
Yes i agree, dont take any chances of not studying anything,
Expect the unexpected. LOL :D
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dont think so,, it only comes in p6's
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growth
thanks...was thinking of in-depth stuff but it turned out to be the basic thing...hehe
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okay is this organ transplant thingy in our syllabus
-
okay is this organ transplant thingy in our syllabus
yup very much .. u wanna know abt it ??
-
yup very much .. u wanna know abt it ??
not really...my doubt is tht y do the antibiotics only efect bacteria nad not viruses ///???
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not really...my doubt is tht y do the antibiotics only efect bacteria nad not viruses ///???
Antibiotics prevent the bacterial cell wall from developing hence preventing bacterial growth. however, viruses do not have cell walls, so the antibiotics do not attack them.
This came in Paper 6...It ain't coming tom, for sure!
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Antibiotics prevent the bacterial cell wall from developing hence preventing bacterial growth. however, viruses do not have cell walls, so the antibiotics do not attack them.
This came in Paper 6...It ain't coming tom, for sure!
haha i noe it wont come again just had a doubt...Thanks aneways
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Explain why food chains have fewer than 5 trophic levels.
The answer's pretty obvious, but can anyone explain this in a manner fit for an IG paper. XD
Man I hate ecology :(
-
chem doubt
sumtyms for mcqs dey ask which 1 is a reversible reaction <n the forwd n bckwrd rctn arrows are not dere >
hw do we noe which 1 is a revesible rctn???????
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Explain why food chains have fewer than 5 trophic levels.
The answer's pretty obvious, but can anyone explain this in a manner fit for an IG paper. XD
Man I hate ecology :(
for a 2 mark q...this should work...this is becaz the energy in the chain produced by the producers is lost at each trophic level and by the tyme it reaches the 5th it is all used up..so there wont be enough energy left for an other level :)
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chem doubt
sumtyms for mcqs dey ask which 1 is a reversible reaction <n the forwd n bckwrd rctn arrows are not dere >
hw do we noe which 1 is a revesible rctn???????
can u give example plz..
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Explain why food chains have fewer than 5 trophic levels.
The answer's pretty obvious, but can anyone explain this in a manner fit for an IG paper. XD
Man I hate ecology :(
lol its is the 'stupid' answer .. because energy is lost in huge amounts as you go up the trophic levels, due to metabolism, heat loss n stuff .. further down the chain suppose 6 level .. u hav to eat LOTS of food !!! ;)
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Hey guys, do v need to learn a sigmoid curve or something? Like its phases and everything? If yes can someone explain it? Thanks a lot! :D
-
can u give example plz..
reaction of nitrogen and hydrogen
usually all decomposition carbonate reactions are reversible
sulfur dioxide and oxygen reaction to form SO3
oxygen to ozone .. many ..
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Hey guys, do v need to learn a sigmoid curve or something? Like its phases and everything? If yes can someone explain it? Thanks a lot! :D
You should be able to learn this.
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Hey guys, do v need to learn a sigmoid curve or something? Like its phases and everything? If yes can someone explain it? Thanks a lot! :D
YES !!
(http://image.tutorvista.com/content/plant-growth-movements/growth-curve.jpeg)
http://www.bbc.co.uk/schools/gcsebitesize/geography/population/
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Hey guys, do v need to learn a sigmoid curve or something? Like its phases and everything? If yes can someone explain it? Thanks a lot! :D
I'll give you an example of phases in bacterial growth.
Lag phase: When doubling of the numbers has little effect as the numbers are so small. Bacteria take up water and nutrients, make new cytoplasm, DNA and enzymes.
Log phase: When the population is increasing rapidly. The populatoin increases by doubling and there are no limiting factors, such as food or water.
Stationary phase: When bacterial cells are dying at the same rate at which they are being produced. This may be because of shortage of food or because waste products are building up.
Death phase: When more cells are dying than are being produced, so the population declines. Causes of death may be lack of food, shortage of oxygen or a build-up of toxic waster products.
Hope that helps!
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for a 2 mark q...this should work...this is becaz the energy in the chain produced by the producers is lost at each trophic level and by the tyme it reaches the 5th it is all used up..so there wont be enough energy left for an other level :)
thanks :)
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YES !!
(http://image.tutorvista.com/content/plant-growth-movements/growth-curve.jpeg)
http://www.bbc.co.uk/schools/gcsebitesize/geography/population/
Thanks!!! :P
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lol its is the 'stupid' answer .. because energy is lost in huge amounts as you go up the trophic levels, due to metabolism, heat loss n stuff .. further down the chain suppose 6 level .. u hav to eat LOTS of food !!! ;)
i wish i was at the sixth trophic level. It wud b an 'all u can eat' for me. ;) LOL...thanks!
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:o :o :o
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Lol...THANKS EVERYONE.. :p and yeah i was going through the syllabus.. :)
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Do we need to know the stages for meiosis and mitosis? I mean even briefly. I learnt them in great detail earlier only to realise they havent even been hinted at in the syllabus. >:(
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Do we need to know the stages for meiosis and mitosis? I mean even briefly. I learnt them in great detail earlier only to realise they havent even been hinted at in the syllabus. >:(
No you don't. Look in the syllabus, you only need to know definitions I quote: "details of stages are NOT required".
Definitions:
Mitosis: Nuclear division giving rise to genetically identical cells in which the chromsome number is maintained by the exact duplication of chromosomes.
Meiosis: Reduction division in which the chromosome number is halved from diploid to haploid.
Hope tha thelps!
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HEY! plz help out for tis question:
Ammonium chloride is heated wit substance X. The gas given off turns damp litmus paper blue.
Which type of substance is X?
A. Acid
B. Base
C. Metal
D. Salt
:-\ :-\ :-\
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HEY! plz help out for tis question:
Ammonium chloride is heated wit substance X. The gas given off turns damp litmus paper blue.
Which type of substance is X?
A. Acid
B. Base
C. Metal
D. Salt
:-\ :-\ :-\
Base - sodium hydroxide
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check the syllabus. You need to know the radical tests of certain cations and anions. Memorise them.
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check the syllabus. You need to know the radical tests of certain cations and anions. Memorise them.
Yes, learn this.
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i was looking for this but couldn't find it
thanks ivo.
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i was looking for this but couldn't find it
thanks ivo.
Its on the last page of the Paper 5 practical test for IGCSE CHEM ;D
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oh ok :P I wouldn't know :P
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No you don't. Look in the syllabus, you only need to know definitions I quote: "details of stages are NOT required".
Definitions:
Mitosis: Nuclear division giving rise to genetically identical cells in which the chromsome number is maintained by the exact duplication of chromosomes.
Meiosis: Reduction division in which the chromosome number is halved from diploid to haploid.
Hope tha thelps!
yep..it took a load off my mind :)
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Its also on page 27 of the chemistry syllabus for 2010
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Can someone tell me what we need to know about the brain?
-
any any one explain
QA7(c) paper=M/J 07
-
any any one explain
QA7(c) paper=M/J 07
bio/chem?
-
bio/chem?
chem....and also please explain B11(d) of same paper
-
link please? what A and B are u talking about??
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Can someone tell me what we need to know about the brain?
Well, you need to know the main parts of the brain and its functions.
- Cerebrum (fore brain) => Coordination between organs, control over voluntary actions and sensation
- Cerebellum (Hind brain) => Balance and instincts
- Medulla (Hind brain) => Joins brain to spinal cord and controls unconscious activities like heartbeats, breathing and peristalsis.
- Hypothalamus - (Fore brain) => Monitors changes in the body
- Pituitary gland (fore brain) => Manufactures hormones and releases them into the blood, Growth and development, coordination and it is instructed by the Hypothalamus.
I think this is all u need to know.. :)
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I always get confused with mutation and inheritance when it comes to Sickle Cell Anaemia and Down's Syndrome.
In Sickle Cell Anaemia, do u INHERIT the faulty gene? Or does the normal haemoglobin gene undergo mutation? Or is it mutated while inheritance?
Can someone simplify the concept of these two conditions please?
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Could someone please help me with the following question:
BIO P3:
1) nov 2007 no. 4c
2) jun 2007 no. 4ii (diff between source and sink?)
3) jun 2006 no. 5c
4) nov 2005 no. 6c
5) quorn vs. mycoprotein...which one is produced by bacteria and which one's produced by fungus?
Sorry for all my question!
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I always get confused with mutation and inheritance when it comes to Sickle Cell Anaemia and Down's Syndrome.
In Sickle Cell Anaemia, do u INHERIT the faulty gene? Or does the normal haemoglobin gene undergo mutation? Or is it mutated while inheritance?
Can someone simplify the concept of these two conditions please?
Well, sickel cell anaemia is a faulty allele tht is present in ppl.. and it is inherited. And downs syndrome usually happens in older women. instead of the usual 23 pairs, 24 are made and after fertilization, the zygote gets 47. Um... yeah.. :P
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I always get confused with mutation and inheritance when it comes to Sickle Cell Anaemia and Down's Syndrome.
In Sickle Cell Anaemia, do u INHERIT the faulty gene? Or does the normal haemoglobin gene undergo mutation? Or is it mutated while inheritance?
Can someone simplify the concept of these two conditions please?
sickle cell anemia is a gene mutaion and you can inherit it.
down's syndrome is a chromosome mutation.
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please explain following question......
chemistry paper 2......M/J/07
section A
Q7 part C
section B
Q11 part D
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i'm soo dead....tomorrow i've got bio p3, gce as-maths M1 and C1 :(
-
please explain following question......
chemistry paper 2......M/J/07
section A
Q7 part C
section B
Q11 part D
sorry i'm not doing p2...but good luck!
-
Guys, the problem is i don't have the papers now. It's over a year since i gave the igz. If possible upload the papers or simply paste the question here.
Thanks
-
http://www.srepapmaxeeeerf.org/O%20Level/Chemistry/CIE/2007%20Jun/5070_s07_qp_2.pdf
this is the link to paper.....
please explain Q7c and 11d
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Could someone please help me with the following question:
BIO P3:
1) nov 2007 no. 4c
2) jun 2007 no. 4ii (diff between source and sink?)
3) jun 2006 no. 5c
4) nov 2005 no. 6c
5) quorn vs. mycoprotein...which one is produced by bacteria and which one's produced by fungus?
Sorry for all my question!
1) Vasoconstriction is the answer. This is when the capillaries near the surface of the skin gets narrower so that less heat is lost.
2)Source is the place where a particular substance is obtained from. Sink is the final destination of tht substance.
3)No it isn't genetic enginnering as tht is taking a DIFFERENT gene from an organism and placing it in another organism. Here they just wants to make the gene more active. (I am not sure of this ans check with the MS :P )
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yep..it took a load off my mind :)
but hey go do de pastppr n u vil find question abut it once i dunt remember de year but it sureli did cum :) ;D
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I'm pretty sure we don't need to know anything about the brain (except for the fact that it's part of the central nervous system with the spinal cord)? Unless you're taking O-Level, which you're not, as far as I know?
OH.. r u serious we dont need to learn this for Igcse? OMG... i didnt know tht.. :O
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I'll give you an example of phases in bacterial growth.
Lag phase: When doubling of the numbers has little effect as the numbers are so small. Bacteria take up water and nutrients, make new cytoplasm, DNA and enzymes.
Log phase: When the population is increasing rapidly. The populatoin increases by doubling and there are no limiting factors, such as food or water.
Stationary phase: When bacterial cells are dying at the same rate at which they are being produced. This may be because of shortage of food or because waste products are building up.
Death phase: When more cells are dying than are being produced, so the population declines. Causes of death may be lack of food, shortage of oxygen or a build-up of toxic waster products.
Hope that helps!
hey but still wats de difference btwen lag n log can u plz explain ???:)
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1) Vasoconstriction is the answer. This is when the capillaries near the surface of the skin gets narrower so that less heat is lost.
2)Source is the place where a particular substance is obtained from. Sink is the final destination of tht substance.
3)No it isn't genetic enginnering as tht is taking a DIFFERENT gene from an organism and placing it in another organism. Here they just wants to make the gene more active. (I am not sure of this ans check with the MS :P )
Thank you VERYYY much!!!!!
-
Hey guys
i kno i have mark schemes but can some1 plz give me a model answer for O/N 05 p3 q6 c (biology) PLZ
it says ref. and ref. i kno wat it means but i wud like a full answer
thx in advance :)
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please explain following question......
chemistry paper 2......M/J/07
section A
Q7 part C
section B
Q11 part D
B11D
PROPANOL+ OXIDIZING AGENT = PROPANOIC ACID + WATER
propanol + 2 - = C3H7OH + 2
- = CH3CH2COOH + H2O
A7C - im not sure, wait for nid..
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hey but still wats de difference btwen lag n log can u plz explain ???:)
lag phase: Initially, the increase is slow because we start with only few organisms. The rise is gentle as there are few reproducing individuals. Besides the population density being low, organisms are adapting to the environment.
log phase: the organisms have estavlished themselves and growth rate has become rapid. The population increases at an exponential/logarithmic rate. Birth rate exceed death rate, There are no limiting factors as food and space is in abundance. The population grows at its maximum potential rate, doubling in size every generation.
-
B11D
PROPANOL+ OXIDIZING AGENT = PROPANOIC ACID + WATER
propanol + 2 - = C3H7OH + 2
- = CH3CH2COOH + H2O
A7C - im not sure, wait for nid..
Thanks
-
Hey guys
i kno i have mark schemes but can some1 plz give me a model answer for O/N 05 p3 q6 c (biology) PLZ
it says ref. and ref. i kno wat it means but i wud like a full answer
thx in advance :)
i have the same question
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lol, no we don't need to know all the functions and stuff ;) it's not mentioned anywhere in the syllabus, i'm 1000000% sure.
should be easier for you now!
good luck :) i'm sure you'll do well
Hahah.. well im glad all of them aren't there.. :)
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Could someone please help me with the following question:
BIO P3:
1) nov 2007 no. 4c
2) jun 2007 no. 4ii (diff between source and sink?)
3) jun 2006 no. 5c
4) nov 2005 no. 6c
5) quorn vs. mycoprotein...which one is produced by bacteria and which one's produced by fungus?
Sorry for all my question!
I was just solving 07 and 06
For your first Question
1)They want want the place where the diameter is reduced, How and why
I said Just after the stomach the diameter is reduced by sphincter muscles so food can be digested then passed
on the doudenum. (hope i'm correct, yes i know its sounds wierd vasconstriction is better, comment anyone)
2)Have no idea and want to know :-\
3)Have a anwser but want to hear it from someone else
Q:An article in a school science magazine stated, ‘Many plants contain genes which
enable them to pump salts out of their roots. These genes can be made more active by
genetic engineering, enabling the plants to remove salts before the plants are damaged.’
Explain whether you think that the process described in the article above is an example
of genetic engineering.
4)Outline how enzymes can be manufactured for use in biological washing powders.
5) quorn is produced by bacteria, mycroprotien from fungus
yes i was useless lol ;D
-
Thank you VERYYY much!!!!!
No problem.. :)
-
I was just solving 07 and 06
For your first Question
1)They want want the place where the diameter is reduced, How and why
I said Just after the stomach the diameter is reduced by sphincter muscles so food can be digested then passed
on the doudenum. (hope i'm correct, yes i know its sounds wierd vasconstriction is better, comment anyone)
2)Have no idea and want to know :-\
3)Have a anwser but want to hear it from someone else
Q:An article in a school science magazine stated, ‘Many plants contain genes which
enable them to pump salts out of their roots. These genes can be made more active by
genetic engineering, enabling the plants to remove salts before the plants are damaged.’
Explain whether you think that the process described in the article above is an example
of genetic engineering.
4)Outline how enzymes can be manufactured for use in biological washing powders.
5) quorn is produced by bacteria, mycroprotien from fungus
yes i was useless lol ;D
thanks! you were not useless, but very helpful...for no. 3, check your ans by the ans given by Raywin: "No it isn't genetic enginnering as tht is taking a DIFFERENT gene from an organism and placing it in another organism. Here they just wants to make the gene more active."
and i guess its right.
-
I was just solving 07 and 06
For your first Question
1)They want want the place where the diameter is reduced, How and why
I said Just after the stomach the diameter is reduced by sphincter muscles so food can be digested then passed
on the doudenum. (hope i'm correct, yes i know its sounds wierd vasconstriction is better, comment anyone)
2)Have no idea and want to know :-\
3)Have a anwser but want to hear it from someone else
Q:An article in a school science magazine stated, ‘Many plants contain genes which
enable them to pump salts out of their roots. These genes can be made more active by
genetic engineering, enabling the plants to remove salts before the plants are damaged.’
Explain whether you think that the process described in the article above is an example
of genetic engineering.
4)Outline how enzymes can be manufactured for use in biological washing powders.
5) quorn is produced by bacteria, mycroprotien from fungus
yes i was useless lol ;D
and also the second one the answer was given by Raywin: "Source is the place where a particular substance is obtained from. Sink is the final destination of tht substance."
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@ Burhan.arshad - OK PROBABLY THIS IS THE ANSWER..
Transition metal carbonates decompose faster because theyre not stable when heated.
the transition metals carbonates in the list are of zinc and copper.
Zinc is more reactive than copper, thus copper carbonate will get decomposed the fastest. = 25seconds = U
Next will be zinc = Z = 50seconds
Our of calcium magnesium and sodium, the reactivity is this like this-> Sodium, calcium , magnesium ...(sodium being the most reactive)
thus magnesium carbonate will decompose after copper and zinc...Magnesium carbonate = 100seconds = V
Then will be calcium carbonate = 300 seconds = X
and last will be of the most reactive metal sodium carbonate = Y = more than 1000seconds.
-
What is quorn and mycroprotien ? :S
-
I'm pretty sure we don't need to know anything about the brain (except for the fact that it's part of the central nervous system with the spinal cord)? Unless you're taking O-Level, which you're not, as far as I know?
its bettrr to know the basics juzt in case
Medulla: controls heartbeat and breathing
Cerebral cortex: controls intelligence n motor action
Cerebellum: balance of body is monitored
Pituitary gland: secretes the hormones MSH and ADH
thats it :D
-
http://www.srepapmaxeeeerf.org/O%20Level/Chemistry/CIE/2007%20Jun/5070_s07_qp_2.pdf
this is the link to paper.....
please explain Q7c and 11d
The more reactive metals take longer to dissociate.
Reactivity series from most reactive to least reactive
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
Platinum
The ones in bold are of our concern
Least time was for U.25sec. The least reactive metal among the ones used is Copper
The next was Z 50sec. This would be Zinc
In the same way...you're just moving up the series
Then V would be Magnesium
X would be calcium
Y would be sodium
Hope you got that.
-
they are both SCP (single cell protiens)
-
they are both SCP (single cell protiens)
Thx.. :)
-
Can any1 pls xplain me TRANSLOCATION the whole concept, including its source and sink in difrent conditions
-
What is quorn and mycroprotien ? :S
i just realised that quorn is the brand name of mycoprotein (so basically they are the same thing). mycoprotein is made by the mould fungus. Mycoprotein is a substitute for meat (so its popular among vegetarians).
Single cell protein (SCP) is made by yeasts.
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Can any1 pls xplain me TRANSLOCATION the whole concept, including its source and sink in difrent conditions
Translocation is the movement of the finished food products from the leaves (source) to the rest of the plant for eg: Roots(sink) and yeah these finished products travel through the Phloem. Oh and in the early stages of the plant the SOURCE is the cotyledons and the SINK is the roots (germination stage). Yeah this is all u need to know.. :)
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i just realised that quorn is the brand name of mycoprotein (so basically they are the same thing). mycoprotein is made by the mould fungus. Mycoprotein is a substitute for meat (so its popular among vegetarians).
Single cell protein (SCP) is made by yeasts.
Ohh.. thanks.. :)
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Can any1 pls xplain me TRANSLOCATION the whole concept, including its source and sink in difrent conditions
Xylem tissue tansports water - dead xylem cells form tubes through which water is drawn. The walls of xylem tubes are waterproofed with a substance called lignin.
Phloem tissue transports food in flowering plants. Living phloem consists of tubes of sieve cells and companion cells.
-
Ohh.. thanks.. :)
no problem :D
-
Hey guys
i kno i have mark schemes but can some1 plz give me a model answer for O/N 05 p3 q6 c (biology) PLZ
it says ref. and ref. i kno wat it means but i wud like a full answer
thx in advance :)
some1 plz i rely need this concept for othr questions
-
Xylem tissue tansports water - dead xylem cells form tubes through which water is drawn. The walls of xylem tubes are waterproofed with a substance called lignin.
Phloem tissue transports food in flowering plants. Living phloem consists of tubes of sieve cells and companion cells.
Transport of water and minerals
- Root hairs absorb water from the soil by osmosis; mineral ions are actively transported into the root
- Water passes through the root tissue into the xylem by osmosis
- Water travels through the xylem of the root and stem in unbroken columns - the transpiration system
- Water moves through the xylem of the leaf stalk and veins of the leaf
- Water evaporates into the large air spaces within the leaf - the air spaces are saturated with water vapour
- The concentration of water vapour in the atmosphere is lower that that in the air spaces - water vapour diffuses from the leaf through the stomata; the process is called transpiration
- Water lost by cells through evaporation is replaced with water drawn though the cells by osmosis - cells next to the xylem draw water from the xylem by osmosis
Plants lose water through transpiration and gain water through its uptake by the roots. If the loss is greater than the gain then the stomata close and transpiration is reduced. If the loss continues then the cells of the plant lose turgor (rigidity) and the plant wilts.
Different factors increase the rate of transpiration:
- temperature
- wind velocity
- light intensity
Humidity decreases the rate of transpiration.
-
guys i'm so screwed for bio tomorrow :( i spent most of today studying for accounting and i'm REALLY not ready for bio.. like i understand everything, but i haven't really memorized specific topics well.. and i've only done 2 past papers! i still need to review more for accounting and BOTH are tomorrow morning so i have no time to study in the morning and and like 2 or 3 more hours max tonight.
what do i do??? someone help please :(
Heyy go over all the plant stuff because i think therell be a question on plants since nothing came in paper 6. do ecology, genetics, excretion, reproduction. I think the other stuff is pretty easy but do these things for sure!
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Can any1 pls xplain me TRANSLOCATION the whole concept, including its source and sink in difrent conditions
Xylem and phloem carry out long-distance transportation. They are collected together in groups in the vascular bundles.
Translocation is the of the movement of sucrose and amino acids in phloem from regions of production (source) to regions of storage OR to regions of
utilisation in respiration or growth(sinks)
-
From syllabus:
'describe the advantages and disadvantages of breast-feeding compared with bottle-feeding using formula milk'
i know two advantage of breast milk is that the milk have antibodies and balnced diet, anymore advantage?
are the only disadvantage of breast-feeding are social disadvantage(e.g. its not socially acceptable to breast-feed in public places)?
-
Transport of water and minerals
- Root hairs absorb water from the soil by osmosis; mineral ions are actively transported into the root
- Water passes through the root tissue into the xylem by osmosis
- Water travels through the xylem of the root and stem in unbroken columns - the transpiration system
- Water moves through the xylem of the leaf stalk and veins of the leaf
- Water evaporates into the large air spaces within the leaf - the air spaces are saturated with water vapour
- The concentration of water vapour in the atmosphere is lower that that in the air spaces - water vapour diffuses from the leaf through the stomata; the process is called transpiration
- Water lost by cells through evaporation is replaced with water drawn though the cells by osmosis - cells next to the xylem draw water from the xylem by osmosis
Plants lose water through transpiration and gain water through its uptake by the roots. If the loss is greater than the gain then the stomata close and transpiration is reduced. If the loss continues then the cells of the plant lose turgor (rigidity) and the plant wilts.
Different factors increase the rate of transpiration:
- temperature
- wind velocity
- light intensity
Humidity decreases the rate of transpiration.
Transport of food
- The concentration of sugar in the leaf is often lower than the concentration of sugar in the upper ends of the sieve tubes. As a result sugar has to move from the leaf into the sieve tubes by active transport.
- Osmosis draws water from the xylem and increases the pressure in the sieve tubes. As a result sugar solution moves to all parts of the plant through sieve tubes - the process is called translocation - the companion cells support the fuction of sieve cells.
- Pressure in the sieve tubes drops as cells use sugar or store it as starch (e.g. in root cells)
Sugars are used for:
- respiration
- making starch which is a store of food
- making cellulose which is a component of cell walls
- reacting with nitrates to form proteins
-
4)Outline how enzymes can be manufactured for use in biological washing powders.
Sterilise a fermenter, add nutritive material, introduce bacteria and allow to multiply. Then remove bacteria from fermenter and extract enzymes.
-
in chemistry for paper 1 from which year i should practice them
urgently reply me
-
in chemistry for paper 1 from which year i should practice them
urgently reply me
I would suggest from 2009 onwards to as much as possible. :)
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From syllabus:
'describe the advantages and disadvantages of breast-feeding compared with bottle-feeding using formula milk'
i know two advantage of breast milk is that the milk have antibodies and balnced diet, anymore advantage?
are the only disadvantage of breast-feeding are social disadvantage(e.g. its not socially acceptable to breast-feed in public places)?
Breast feeding:
- develops emotional bond with mother
- contains all types of food except iron in the right proportions (baby is born with iron stored in the liver)
- contains antibodies from the mother which helps the baby to fight infections and possibly develop immunity to any sickness the mother has suffered from
- is at the right temperature
- increases upto 1 litre a day to meet the demands of the baby
- free from bacteria
- readily available
Bottle feeding:
- Contains more sodium, protein and phosphorous and less vitamins
- may not be at the right temperature
- may contain bacteria
- baby can be fed by anyone and not just by the mother
- needs time to be prepared
-
Hi, I've got a question.
When plants gain water, can they gain it from active transport. Say if water potential is greater in root hair cells than in soil, surely water can still move up the concentration gradient. So is there such thing as active transport of water?
-
From syllabus:
'describe the advantages and disadvantages of breast-feeding compared with bottle-feeding using formula milk'
i know two advantage of breast milk is that the milk have antibodies and balnced diet, anymore advantage?
are the only disadvantage of breast-feeding are social disadvantage(e.g. its not socially acceptable to breast-feed in public places)?
Advantages of breastfeeding.
- Breastmilk is made naturally and is therefore free
- Mothers who breastfeed have a much lower chance of developing female cancers
Disadvantages of breastfeeding
- Breastfeeding mothers require to restrict their diet
- Fathers feel left-out of the feeding process
Advantages of Formula Feeding
- Formula is not as easily digested as breast milk, thus allowing the baby to be full for longer and thus the baby needs fewer feeding per day
- Mothers can relax while someone else takes care of the baby
- Bottle feeding is more convenient for mothers who are unconformable breastfeeding in public['li]
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Hi, I've got a question.
When plants gain water, can they gain it from active transport. Say if water potential is greater in root hair cells than in soil, surely water can still move up the concentration gradient. So is there such thing as active transport of water?
Root hairs absorb water from the soil by osmosis; mineral ions are actively transported into the root
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and also the second one the answer was given by Raywin: "Source is the place where a particular substance is obtained from. Sink is the final destination of tht substance."
NOV 2006 q5c
its a an example of genetic engineering as the gene that enables de the plants to pump salt out of de root is removed 4rm one species and inserted into another plant its den allowed 2 reproduce n de genetic engneers make this gene efficient as b4 de plant gets modified not DAMAGED de salts are pump up it doesnt get accumulated in de plant de get used up
Outline how enzymes can be manufactured for use in biological washing powders. de answer 4 this is
two types of microorgansiums can be used to manfacture enzymes fungi and bacteria using the fermenter it is a large sterile container with a stirrer and a pipe to add feedstock (molasses or steep liquor) and air pipes to blow air into de mixture. the microorgansium r added n de liquid is maintained at 26*C and a ph 5-6 de enzymes produced may be extracellular( de extracted by filtering from de feedstock)or intracellular (filtered 4rm feed stock den crushed and washed wid water. de enzymes r noe in solution
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No, i dont think they can absorb water by active transport. It only implys for minerals which is essential for the plant...
-
From syllabus:
'describe the advantages and disadvantages of breast-feeding compared with bottle-feeding using formula milk'
i know two advantage of breast milk is that the milk have antibodies and balnced diet, anymore advantage?
are the only disadvantage of breast-feeding are social disadvantage(e.g. its not socially acceptable to breast-feed in public places)?
advantages of breast milk: right probortion of protein, fat, sugar, vitamis and salts for fetus to grow, contains antibodies, supplied at correct body temp and is free from bacteria.
-
Hi, I've got a question.
When plants gain water, can they gain it from active transport. Say if water potential is greater in root hair cells than in soil, surely water can still move up the concentration gradient. So is there such thing as active transport of water?
nope water always moves by osmosis
are we allowed 2 write anything on the blank pages at the end of the qpaper eg working
:-\
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nope water always moves by osmosis
are we allowed 2 write anything on the blank pages at the end of the qpaper eg working
:-\
Of course you are! But don't write any information that you want scanned and marked.
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NOV 2006 q5c
its a an example of genetic engineering as the gene that enables de the plants to pump salt out of de root is removed 4rm one species and inserted into another plant its den allowed 2 reproduce n de genetic engneers make this gene efficient as b4 de plant gets modified not DAMAGED de salts are pump up it doesnt get accumulated in de plant de get used up
Outline how enzymes can be manufactured for use in biological washing powders. de answer 4 this is
two types of microorgansiums can be used to manfacture enzymes fungi and bacteria using the fermenter it is a large sterile container with a stirrer and a pipe to add feedstock (molasses or steep liquor) and air pipes to blow air into de mixture. the microorgansium r added n de liquid is maintained at 26*C and a ph 5-6 de enzymes produced may be extracellular( de extracted by filtering from de feedstock)or intracellular (filtered 4rm feed stock den crushed and washed wid water. de enzymes r noe in solution
thanks!
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No, i dont think they can absorb water by active transport. It only implys for minerals which is essential for the plant...
Yup... exactly what I said. :)
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From syllabus:
'describe the advantages and disadvantages of breast-feeding compared with bottle-feeding using formula milk'
i know two advantage of breast milk is that the milk have antibodies and balnced diet, anymore advantage?
are the only disadvantage of breast-feeding are social disadvantage(e.g. its not socially acceptable to breast-feed in public places)?
advantage of breast feeding:bond between mother and baby
disadvantage of bottled milk: they might be unsterilized and the baby might get sick
can never supply the baby with the right amount of everything
might not suit the baby
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Can someone tell me what the role and what hormones for menstrual cycle.
Also, stuck on this question:
-
Can someone tell me what the role and what hormones for menstrual cycle.
Also, stuck on this question:
Oestrogen - It is from the ovary, stimulates division of cells lining uterus which thickens - its blood supply increases.
Progesterone - It is from the corpus luteum, it maintains the thickening of the lining of the uterus.
-
please explain ether linkages and how ether is formed.....
-
Can someone tell me what the role and what hormones for menstrual cycle.
Also, stuck on this question:
Hormonal method of birth control
A pill is consumed everyday which contains the female sex hormones oestrogen and progesterone. The hormones are like those that are made when a woman is pregnant, and stop egg production.
Chemical method of birth control
Chemicals called spermicides, which kill sperms, are used. They are best used in combination with another method.
-
Can someone tell me what the role and what hormones for menstrual cycle.
Also, stuck on this question:
Fertility drugs:
LH- Luteinizing Hormone- used to stimulate ovulation, and cause multiple release of ova
FSH: causes the development of Graafian follicles in the ovaries
Chemical methods of Birht Control:
Oestrogen: prevents release of LH, hence preventing ovulation.
Progesterone: Maintains the lining of the uterus, and prevents it from shedding. Also inhibits release of FSH and hence development of follicles.
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please explain ether linkages and how ether is formed.....
Carboxylic acids react with alcohols to form esters. Concentrated sulphuric acid is used as a catalyst in this reaction.
ethanoic acid + ethanol will give ethyl ethanoate + water. This is a reversible reaction.
For more information on esters, go to Page 283 of the Chemistry Revision Guide (http://thenightdreamer.wordpress.com/2009/11/11/chemistry-guide/) that I got from SF itself. The link will allow you to download the guide from The Nightdreamer Inc.
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Fertility drugs:
LH- Luteinizing Hormone- used to stimulate ovulation, and cause multiple release of ova
FSH: causes the development of Graafian follicles in the ovaries
Chemical methods of Birht Control:
Oestrogen: prevents release of LH, hence preventing ovulation.
Progesterone: Maintains the lining of the uterus, and prevents it from shedding. Also inhibits release of FSH and hence development of follicles.
By the way, are follicle and ovum the same thing? Which is released every month?
-
Fertility drugs:
LH- Luteinizing Hormone- used to stimulate ovulation, and cause multiple release of ova
FSH: causes the development of Graafian follicles in the ovaries
Chemical methods of Birht Control:
Oestrogen: prevents release of LH, hence preventing ovulation.
Progesterone: Maintains the lining of the uterus, and prevents it from shedding. Also inhibits release of FSH and hence development of follicles.
I checked the Mary Jones textbook and this is the explanation given for chemical birth-control (not the exact wording):
Chemical method of birth control
Chemicals called spermicides, which kill sperms, are used. They are best used in combination with another method.
Maybe the wording used in the question was wrong? Because in the Mary Jones text book the method where hormones are used is called the Hormonal method.
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Question:
Syntheic plant hormones behave in a similar way to auxins. Describe how synthetic
plant hormones are effective as weedkiller. Help anyone :-\
-
Question:
Syntheic plant hormones behave in a similar way to auxins. Describe how synthetic
plant hormones are effective as weedkiller. Help anyone :-\
The synthetic hormones "over-grow" these weeds and eventually these weeds die. thts all.. :)
-
Can anyone clarify the functions of the hormones involved in the menstrual cycle?
LH, FSH, progesterone, and estrogen? It's really confusing...
Also, what's a follicle and what's a corpus luteum???
-
Carboxylic acids react with alcohols to form esters. Concentrated sulphuric acid is used as a catalyst in this reaction.
ethanoic acid + ethanol will give ethyl ethanoate + water. This is a reversible reaction.
For more information on esters, go to Page 283 of the Chemistry Revision Guide (http://thenightdreamer.wordpress.com/2009/11/11/chemistry-guide/) that I got from SF itself. The link will allow you to download the guide from The Nightdreamer Inc.
i am asking about ethers.....not esters.....
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Can someone tell me what the role and what hormones for menstrual cycle.
Also, stuck on this question:
This is the ans from marking scheme:
Fertility drugs: FSH causes ovaries to produce more eggs, thus increasing chance of fertilization.
Chemical: contraceptive pill prevents FSH release. This prevents egg development so ovulation is prevented.
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i am asking about ethers.....not esters.....
Oops. Sorry, I misread. :-[
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i am asking about ethers.....not esters.....
Simple, symmetrical ethers can be formed by the acid-catalyzed condensation of two molecules of an alcohol. For example, diethyl ether will form is ethanol is treated with concentrated sulfuric acid.
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The synthetic hormones "over-grow" these weeds and eventually these weeds die. thts all.. :)
So if synthetic plant hormones over grow the weed and kill them in what
way is this similar to auxin ???
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This is the ans from marking scheme:
Fertility drugs: FSH causes ovaries to produce more eggs, thus increasing chance of fertilization.
Chemical: contraceptive pill prevents FSH release. This prevents egg development so ovulation is prevented.
But in the Mary Jones textbook on Page 81, Chemical method is described as using chemicals. The method where hormones are used is called the Hormonal method.
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Simple, symmetrical ethers can be formed by the acid-catalyzed condensation of two molecules of an alcohol. For example, diethyl ether will form is ethanol is treated with concentrated sulfuric acid.
can u explain in more details?
with equations?
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can u explain in more details?
with equations?
I actually got the answer from the follwoing site: http://www.ferris.edu/htmls/academics/course.offerings/balandap/Organic/CHEM124/Problems/Ethers_and_epoxides_ANS.htm
it has equations.
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I actually got the answer from the follwoing site: http://www.ferris.edu/htmls/academics/course.offerings/balandap/Organic/CHEM124/Problems/Ethers_and_epoxides_ANS.htm
it has equations.
just press ctrl+F and type formation of ethers....its sumwhere in the middle of the page...
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just press ctrl+F and type formation of ethers....its sumwhere in the middle of the page...
Thanks
-
can u explain in more details?
with equations?
Ether is a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether" (CH3-CH2-O-CH2-CH3). Ethers are common in organic chemistry and pervasive in biochemistry, as they are common linkages in carbohydrates and lignin.
Try going to the following links to find what specific areas you want answers in.
Chemical properties of ether (http://www.transtutors.com/chemistry-homework-help/ethers/chemical-properties-of-ether.aspx)
Preparation of ethers (http://www.transtutors.com/chemistry-homework-help/ethers/preparation-of-ethers.aspx)
Friedel craft reaction (http://www.transtutors.com/chemistry-homework-help/ethers/friedel-craft-reaction.aspx)
Halogenation of ether (http://www.transtutors.com/chemistry-homework-help/ethers/halogenation-of-ether.aspx)
Hydrolysis of ether (http://www.transtutors.com/chemistry-homework-help/ethers/hydrolysis-of-ether.aspx)
Oxidation of ether (http://www.transtutors.com/chemistry-homework-help/ethers/oxidation-of-ether.aspx)
Peroxide formation (http://www.transtutors.com/chemistry-homework-help/ethers/peroxide-formation.aspx)
Ring substitution in aromatic ethers (http://www.transtutors.com/chemistry-homework-help/ethers/ring-substitution-in-aromatic-ethers.aspx)
Salt formation by ether (http://www.transtutors.com/chemistry-homework-help/ethers/salt-formation-by-ether.aspx)
Williamson synthesis (http://www.transtutors.com/chemistry-homework-help/ethers/williamson-synthesis.aspx)
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But in the Mary Jones textbook on Page 81, Chemical method is described as using chemicals. The method where hormones are used is called the Hormonal method.
hmmm...maybe they add chemicals which behave like estrogen and progesterone in the pills....
-
Thanks
mention not :)
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heyy .. exams 2mrrw wish everyone luckk ..
my question is from may/june 2003 it sayss
a)explain why in some parts of the world, not enough food is available to feed the people living there . (10 marks)
b) describe the use of hormones in foood production
thannks in advance !!!
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hmmm...maybe they add chemicals which behave like estrogen and progesterone in the pills....
Hmm... possible. Here are the exact wordings:
Chemical methods use chemicals called spremicides, which kill sperm. They are best used in combination with another method. For example, spermicides may be inserted into the vagina with a cap.
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hmmm...maybe they add chemicals which behave like estrogen and progesterone in the pills....
chemical method:
spermicides: a gel or foam,kills in the vagina, should be used with a diaphragm or a condom
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Hmm... possible. Here are the exact wordings:
i see...the question surely is confusing....
By the way...can the marking scheme be wrong?
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Hmm... possible. Here are the exact wordings:
sry
didnt see u hd answered
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When added to 20 cm3 of 0.5 M sulphuric acid, which substance would give a neutral solution?
A 20 cm3 of 0.5 M sodium hydroxide
B 10 cm3 of 0.5 M sodium hydroxide
C 40 cm3 of 1.0 M sodium hydroxide
D 20 cm3 of 1.0 M sodium hydroxide
anxer is d.......but how? i think it's a
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heyy .. exams 2mrrw wish everyone luckk ..
my question is from may/june 2003 it sayss
a)explain why in some parts of the world, not enough food is available to feed the people living there . (10 marks)
b) describe the use of hormones in foood production
thannks in advance !!!
y dont u hav a look at the ms .. ?? if u still wan it tell ..
-
can any1 explain how HIV affects the immune system . :) :) :) :)
-
The molar ratio has to be seen.
Reaction is
H2SO4+ 2NaOH--->Na2SO4
Ratio of moles is 1:2
no of moles of sulphuric acid= 0.5 X 20/1000= 0.01
so no of moles of NaOH= 0.02 (twice)
vol of NaOH= 20/1000 dm3
conc= 0.02 X1000/20 = 1 M
Hence D
Try it with the other options...either the vol of conc will not tally with the no of moles.
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Hmm... possible. Here are the exact wordings:
Spermicides is another example of a chemical method. It says so right here in my study guide. The contraceptive pill and spermicides.
Hey...progesterone also prevents the implantation of a bastula (in the guide too).....although I dunno how :S
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Ether is a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether" (CH3-CH2-O-CH2-CH3). Ethers are common in organic chemistry and pervasive in biochemistry, as they are common linkages in carbohydrates and lignin.
Try going to the following links to find what specific areas you want answers in.
Chemical properties of ether (http://www.transtutors.com/chemistry-homework-help/ethers/chemical-properties-of-ether.aspx)
Preparation of ethers (http://www.transtutors.com/chemistry-homework-help/ethers/preparation-of-ethers.aspx)
Friedel craft reaction (http://www.transtutors.com/chemistry-homework-help/ethers/friedel-craft-reaction.aspx)
Halogenation of ether (http://www.transtutors.com/chemistry-homework-help/ethers/halogenation-of-ether.aspx)
Hydrolysis of ether (http://www.transtutors.com/chemistry-homework-help/ethers/hydrolysis-of-ether.aspx)
Oxidation of ether (http://www.transtutors.com/chemistry-homework-help/ethers/oxidation-of-ether.aspx)Ester is formed when alkanoic acid and alcohol reacts under heat, concecentrated sulphuric acid amd catalyst. The COO linkage present in ester is also known as the ester linkage.
For example if methanol and ethanoic acid reacted together, the product would be called methyl ethnoate. When drawing the structure, draw the alkanoic acid first (from left to right), the COO linkage and finally, the alcohol.
Peroxide formation (http://www.transtutors.com/chemistry-homework-help/ethers/peroxide-formation.aspx)
Ring substitution in aromatic ethers (http://www.transtutors.com/chemistry-homework-help/ethers/ring-substitution-in-aromatic-ethers.aspx)
Salt formation by ether (http://www.transtutors.com/chemistry-homework-help/ethers/salt-formation-by-ether.aspx)
Williamson synthesis (http://www.transtutors.com/chemistry-homework-help/ethers/williamson-synthesis.aspx)
-
The molar ratio has to be seen.
Reaction is
H2SO4+ 2NaOH--->Na2SO4
Ratio of moles is 1:2
no of moles of sulphuric acid= 0.5 X 20/1000= 0.01
so no of moles of NaOH= 0.02 (twice)
vol of NaOH= 20/1000 dm3
conc= 0.02 X1000/20 = 1 M
Hence D
Try it with the other options...either the vol of conc will not tally with the no of moles.
Although not essential, but it might be a good idea to include the H2O as well ...
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Although not essential, but it might be a good idea to include the H2O as well ...
woopsy :P
-
can any1 explain how HIV affects the immune system . :) :) :) :)
As far as I know, and I'd appreciate if people would add to it:
The virus attacks the lymphocytes, which act as host cells for these viruses, and replicates its DNA into the nucleas of the lymphocytes, so that they are unable to produce antibodies. In this way these cells are unable to produce an immune response, and so the antibody production part of the immune system is 'deactivated'.
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Hey guys
i kno i have mark schemes but can some1 plz give me a model answer for O/N 05 p3 q6 c (biology) PLZ
it says ref. and ref. i kno wat it means but i wud like a full answer
thx in advance :)
any1????? :-\
-
any1????? :-\
Paper plz :)
-
heyy .. exams 2mrrw wish everyone luckk ..
my question is from may/june 2003 it sayss
a)explain why in some parts of the world, not enough food is available to feed the people living there . (10 marks)
b) describe the use of hormones in foood production
thannks in advance !!!
A.
- Unsuitable climate, temperate, rainfall or relief. Can also be caused due to pollution.
- Natural disasters.
- Poor soil or lack of inorganic ions or fertiliser.
- War or farm redistribution.
- Farmers poorly educated.
B.
- Auxin
- To promote root and shoot formation
- Used with cattle to increase milk production
- Used to increase meat production
- Sprayed onto flowers to induce fruit production
This (http://www.freeexampapers.us/IGCSE/Biology/CIE/2003%20Jun/0610_s03_ms_1+2+3+5+6.pdf) is the mark scheme.
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any1????? :-\
The enzymes are extracted from microorganisms such a bacteria or fungi which are fermented in a fermentation vessel. There is a pipe to add feedstock, an air pipe to blow in air to supply oxygen for the microorganism to respire, and a stirrer to stir the mixture. The process is kept at a temperature of 26 degrees Celsius, at a pH of 5-6. Extracellular enzymes are extracted by filtering them from the feedstock, and intracellular by crushing the microorganisms, then adding water and filtering the mixture so that the enzymes are in solution.
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is this important
USING GENETIC ENGINEERING TO PUT HUMAN INSULIN GENES INTO BACTERIA
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In M/J 09 qs 4)d) Describe how you can find the dry mass of the radish plants. I said place in an oven and heat on medium temperature. The mark scheme just said leave them to dry. Is mine wrong or are both methods correct?
-
r we allowed to write anything on the blank pages at the end of the paper ??? :-\
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is this important
USING GENETIC ENGINEERING TO PUT HUMAN INSULIN GENES INTO BACTERIA
VERY IMPORTANT
http://www.bbc.co.uk/schools/gcsebitesize/science/add_gateway/living/genesrev3.shtml
Restriction endonuclease is used to cut the gene and DNA ligase is used to join the fragments
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is it true that things that didnt came in p6 will come in p3???like reproduction,plant parts and etc...
am i against the sf rules? :-X
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In M/J 09 qs 4)d) Describe how you can find the dry mass of the radish plants. I said place in an oven and heat on medium temperature. The mark scheme just said leave them to dry. Is mine wrong or are both methods correct?
umm....well wat the MS says is usually wat they want. But alternative approaches are also excepted. I feel it wud have been better if u'd have mentioned that we burn it n then measure the dry mass, that's more accurate.
But if we have to use the same radish plant or apparatus (i any general experiment) later in the experiment, then u can't burn it, so u just dry it.
That's what I think at least. My teacher told me burning is the best method to find the dry mass....but not BAKING! XD just kidding
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What's AVP? Any idea anyone?
could u tell where u saw it?
-
What's AVP? Any idea anyone?
alien versus predator ;D
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could u tell where u saw it?
LOL....I guess the pressure is gettin to me.....it means 'ANY VALID POINT'....loooooooooooooool
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LOL....I guess the pressure is gettin to me.....it means 'ANY VALID POINT'....loooooooooooooool
where is it written?
-
As far as I know, and I'd appreciate if people would add to it:
The virus attacks the lymphocytes, which act as host cells for these viruses, and replicates its DNA into the nucleas of the lymphocytes, so that they are unable to produce antibodies. In this way these cells are unable to produce an immune response, and so the antibody production part of the immune system is 'deactivated'.
HIV virus attacks some types of white blood cells (lymphocytes) in the bloodstream, which produce antibodies to kill the antigens (microbes). some lymphocytes are stored in lymph nodes to provide protection against future infection. HIV prevents this immunity being retained, so AIDS surer has no protection against diseases such as tuberculosis (TB) and pneumonia.
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heyy u copied tht fromthe study guide rite??
Thanks nyways!!
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Hahaaa ofcoarse i did my study guides awsome written by Dr, Mohammed afzal ..lol was i suppose 2 say tht with wht i wrote opps sorry i thought it was quite obvious
-
loool ;)
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can som1 plz explain me the diff between continous and discontinous variations ???
-
can som1 plz explain me the diff between continous and discontinous variations ???
Continuous variation: influenced by genes and the environment, resulting in a range of phenotypes between two extremes, e.g. height in humans
Discontinuous variation: caused by genes alone and results in a limited number of distinct phenotypes with no intermediates e.g. A, B, AB, and O blood groups in humans.
Hope that helps ;)
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Continuous variation: influenced by genes and the environment, resulting in a range of phenotypes between two extremes, e.g. height in humans
Discontinuous variation: caused by genes alone and results in a limited number of distinct phenotypes with no intermediates e.g. A, B, AB, and O blood groups in humans.
Hope that helps ;)
hmm i c Thanks
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is it true that things that didnt came in p6 will come in p3???like reproduction,plant parts and etc...
am i against the sf rules? :-X
y everybody ignored me? :'(
-
where is it written?
in the mark schemes. It's usually written for all the general questions..like describe the adv of food additives, use of hormones, issue of world supplies, etc etc...
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y everybody ignored me? :'(
Hey, of course CIE are entitled to put anything in Paper 3, so study the whole syllabus. Nitrogen cycle has been one of the questions for the past 3 sessions!
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in the mark schemes. It's usually written for all the general questions..like describe the adv of food additives, use of hormones, issue of world supplies, etc etc...
There is a glossary of terms used in mark schemes such as AVP, OWTTE in the Oct/Nov 2009 Mark Scheme, take a look ;)!
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y everybody ignored me? :'(
Sorry didnt mean to ignore u...
No gratefully, I don't think SF has problems to making predictions....XD
Well, CIE's unpredictable, but I bet they wanna test our knowledge on other stuff....so yea, it's rather unlikely :)
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Sorry didnt mean to ignore u...
No gratefully, I don't think SF has problems to making predictions....XD
Well, CIE's unpredictable, but I bet they wanna test our knowledge on other stuff....so yea, it's rather unlikely :)
thanks ;D :D
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Sorry didnt mean to ignore u...
No gratefully, I don't think SF has problems to making predictions....XD
Well, CIE's unpredictable, but I bet they wanna test our knowledge on other stuff....so yea, it's rather unlikely :)
Hmm, reproduction or genetics always seems to crop up in one of the topics, and ecology, so get revising on those ;)!
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By the way, guys, anyone noticed that CIE has put more effort into trying to avoid cheating. This year is the first time they introduced variants for Paper 6! Also, I'm guessing more questions will be different between the two variants for Paper 3 (unlike previous years, only 1 or 2 questions were modified)!
I guess it's a much fairer system!
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Guys, just wondering how many past papers have you done for Paper 3? I'm getting nervous, and I've only done 2005-2009, argh too little I guess ::)
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can i tell u chemistry this question
find the empirical formula when 0.5g of H was found to combine with 4.0g of O to form water
can any 1 explain me
urgently reply me as fast as u can
thanks in avance
:'( :'( :'( :'( :'( :'( :'( :'( :'( :'( ??? ??? ??? ??? ??? :'( :'( :'( :'(
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'list the main features used in the classification of the following groups: viruses, bacteria and fungi, and their adaptation to the environment, as appropriate'
im not really sure about this part, could any1 pls correct me if im wrong n add details if possible? thx
virus:
-protein coat
-DNA/RNA strand
-presence of lipids
bacteria:
-plasmid
-no nucleus
fungi:
-cell wall made out of chitin
-hyphae, used to absorb nutrients(is it always from dead organic matters?)
-
There is a glossary of terms used in mark schemes such as AVP, OWTTE in the Oct/Nov 2009 Mark Scheme, take a look ;)!
LOOOOOOOOOOL.....how'd u knw I was doin that ppr ;) XD HAHA
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can i tell u chemistry this question
find the empirical formula when 0.5g of H was found to combine with 4.0g of O to form water
can any 1 explain me
urgently reply me as fast as u can
thanks in avance
:'( :'( :'( :'( :'( :'( :'( :'( :'( :'( ??? ??? ??? ??? ??? :'( :'( :'( :'(
Moles of H: 0.5/1 = 0.5 Moles of O: 4/16 = 0.25
Ratio: 2:1
Therefore, empirical formula: H20
Hope that helps :D
-
thanxs
-
'list the main features used in the classification of the following groups: viruses, bacteria and fungi, and their adaptation to the environment, as appropriate'
im not really sure about this part, could any1 pls correct me if im wrong n add details if possible? thx
virus:
-protein coat
-DNA/RNA strand
-presence of lipids
bacteria:
-plasmid
-no nucleus
fungi:
-cell wall made out of chitin
-hyphae, used to absorb nutrients(is it always from dead organic matters?)
Bacteria also have flagellum, which helps movement of bacteria.
Fungi, talk about spores being produced for reproduction as well.
-
can i tell u chemistry this question
find the empirical formula when 0.5g of H was found to combine with 4.0g of O to form water
can any 1 explain me
urgently reply me as fast as u can
thanks in avance
:'( :'( :'( :'( :'( :'( :'( :'( :'( :'( ??? ??? ??? ??? ??? :'( :'( :'( :'(
divide atomic mass with each mass given in the question for each atom:
Oxygen: 16/4 = 4
Hydrogen: 1/0.5 = 2
then find the proportion of the two values:
hydrogen : oxygen =
4 : 2 =
2 : 1
therefore, theres 2 hydrogen and 1 oxygen, the formula becomes H2O
oops, already answered :P
-
no problem
thanks
-
divide atomic mass with each mass given in the question for each atom:
Oxygen: 16/4 = 4
Hydrogen: 1/0.5 = 2
then find the proportion of the two values:
hydrogen : oxygen =
4 : 2 =
2 : 1
therefore, theres 2 hydrogen and 1 oxygen, the formula becomes H2O
oops, already answered :P
Oh well, at least it's good practice - trying to help others always has its benefits ;D!
-
yes u r right
-
Is the chat room always empty ???
;D
-
Is the chat room always empty ???
;D
Now it's not! :D
-
'describe translocation throughout the plant of applied chemicals, including systemic pesticides'
can any1 help me with this? is the translocation occur in the same way with the translocation of nutrients? thx
-
ok guys gonna get some sleep its 11pm here and i hv to be at school by 8am (bus comes at 6:30am)
may Allah help us all
-
Heyy, can anyone please answer this question: Describe what happens in the soil to convert dead plant material into nitrate ions that
plants can absorb.
how is ammonia converted to nitrites then nitrates?
Where does nitrifying bacteria come in? Can anyone clarify please?
-
'describe translocation throughout the plant of applied chemicals, including systemic pesticides'
can any1 help me with this? is the translocation occur in the same way with the translocation of nutrients? thx
Systemic pesticides are sprayed on the crop plants which absorb them. The pesticides are translocated to all parts of the plant in the phloem. Any insect feeding on any part of the plant will ingest the pesticide with the plant tissue. After a while the insect will ingest enough to kill it. The same happens to fungi growing on or inside any part of a crop plant.
Hope that helps ;)!
-
Heyy, can anyone please answer this question: Describe what happens in the soil to convert dead plant material into nitrate ions that
plants can absorb.
how is ammonia converted to nitrites then nitrates?
Where does nitrifying bacteria come in? Can anyone clarify please?
when dead plants decompose, ammonia from dead plants goes to soil
the nitrifying bacteria converts ammonia to nitrate
pls correct me if im wrong, thx :)
-
Heyy, can anyone please answer this question: Describe what happens in the soil to convert dead plant material into nitrate ions that
plants can absorb.
how is ammonia converted to nitrites then nitrates?
Where does nitrifying bacteria come in? Can anyone clarify please?
Answer to first question:
The dead plant material is subject to decay by decomposing bactera. These bacteria convert amino acids into ammonia (deamination). The nitrifying bactera in the soil convert this ammonia into nitrite, then from nitrite into nitrate in the soil. The plants are then able to absrob these nitrates in the soil.
That's my model answer to the question. Hope that helps :)
-
Answer to first question:
The dead plant material is subject to decay by decomposing bactera. These bacteria convert amino acids into ammonia (deamination). The nitrifying bactera in the soil convert this ammonia into nitrite, then from nitrite into nitrate in the soil. The plants are then able to absrob these nitrates in the soil.
That's my model answer to the question. Hope that helps :)
Thanks. That's a rlly good answer :)
And 'someone' too...thanks!
-
phagocytes r the ones that engulf and digest bacteria
lymphocytes r the one that create antibodies which will kill bacteria
am i right? thx
-
phagocytes r the ones that engulf and digest bacteria
lymphocytes r the one that create antibodies which will kill bacteria
am i right? thx
Yes, and HIV virus attacks the lymphocytes
-
whats the difference between insecticide, herbicide and pesticide?
-
whats the difference between insecticide, herbicide and pesticide?
Pesticides kill pests and disesaes. Herbicides kill weeds. See previous post about systemic pesticides.
-
phagocytes r the ones that engulf and digest bacteria
lymphocytes r the one that create antibodies which will kill bacteria
am i right? thx
Phagocytes use pseudopodia to engulf bacteria, and use enzymes to digest bacteria - a.k.a Phagocytosis.
Lymphocytes produce antibodies that kill bacteria in a variety of ways, including the agglutination of bacteria.
-
Pesticides kill pests and disesaes. Herbicides kill weeds. See previous post about systemic pesticides.
plus insecticides kills insects
this should means that insecticides are also pesticides
-
whats the difference between insecticide, herbicide and pesticide?
well guys good luck for tom! This is it! Major Bio paper! N thanks for ALL ur help, ALL of u! Found this thread rlly helpful :) Goodnight (here in Dubai).....n try not to get nightmares about Bio ;)
-
plus insecticides kills insects
this should means that insecticides are also pesticides
That's right!
-
plus insecticides kills insects
this should means that insecticides are also pesticides
Selective weedkillers are synthetic auxins. The auxins increase the growth of the affected weeds (uncontrolable growth). The weeds cannot provide enough food from photosynthesis to maintain this rate of growth and soon die.
-
Selective weedkillers are synthetic auxins. The auxins increase the growth of the affected weeds (uncontrolable growth). The weeds cannot provide enough food from photosynthesis to maintain this rate of growth and soon die.
to increase food production, auxins r also used right? but is it controlled so that the growth wouldnt be uncontrolled such as what happens to the weeds?
-
Selective weedkillers are synthetic auxins. The auxins increase the growth of the affected weeds (uncontrolable growth). The weeds cannot provide enough food from photosynthesis to maintain this rate of growth and soon die.
I was looking for this, Thanks ;)
-
can somebody tell me about penicillin fermentation???
-
can somebody tell me about penicillin fermentation???
-fungus penicillium are put inside the fermenter
-feedstock(the nutrients(glucose, amino acids)) are inserted to fermenter (glucose for fermentation, amino acids for growth of fungus)
-contents are stirred
-oxygen are inserted in the form of bubbles (provide large surface area for fungus)
-temperature, pH are regulated (regulation to make sure enzyme works in best condition)
-content are extracted
-penicillin are filtered
extra notes:
fermentation is an anaerobic respiration (C6H12O6 --> 2C2H5OH + 2CO2)
-
-fungus penicillium are put inside the fermenter
-feedstock(the nutrients(glucose, amino acids)) are inserted to fermenter (glucose for fermentation, amino acids for growth of fungus)
-contents are stirred
-oxygen are inserted in the form of bubbles (provide large surface area for fungus)
-temperature, pH are regulated
-content are extracted
-penicillin are filtered
24 degrees temp.
pH 6.5
-
compare nervous and hormonal control systems
enzyme used to extract friut juice
thanks .. :)
-
-fungus penicillium are put inside the fermenter
-feedstock(the nutrients(glucose, amino acids)) are inserted to fermenter (glucose for fermentation, amino acids for growth of fungus)
-contents are stirred
-oxygen are inserted in the form of bubbles (provide large surface area for fungus)
-temperature, pH are regulated (regulation to make sure enzyme works in best condition)
-content are extracted
-penicillin are filtered
extra notes:
fermentation is an anaerobic respiration (C6H12O6 --> 2C2H5OH + 2CO2)
thanks!!!
-
compare nervous and hormonal control systems
enzyme used to extract friut juice
thanks .. :)
nervous system: fast, effect lasts for a short period, use electrical impulses
hormonal: slow, effect lasts for a long time, use chemicals(hormones)
the enzyme used is pectinase, though i don't know how it works
-
nervous system: fast, effect lasts for a short period, use electrical impulses
hormonal: slow, effect lasts for a long time, use chemicals(hormones)
the enzyme used is pectinase, though i don't know how it works
pectinase !! yea i remember now .. thanks +rep ;)
-
pectinase !! yea i remember now .. thanks +rep ;)
can any1 tell how the pectinase helps in extracting fruit juice? thx
-
can any1 tell how the pectinase helps in extracting fruit juice? thx
These break down pectin, a polysaccharide(glucose) that is found in the cell walls of plants .. i remember this
-
plz what is a limiting factor
-
plz what is a limiting factor
Limiting factor is something which tends to limit say photosynthesis in a plant .
eg
1. on a bright sunny day the stomata of the leaves close to prevent loss of water. So concentration CO2 acts as a limiting factor as it cannot reach the palisade cells for photosynthesis.
2.if there is abundant of CO2 but temp is less so the enzymes cannot work so temp. is a limiting factor
3.on a cloudy day 'light intensity' acts as a limiting factor as photosynthesis require light(energy)
-
Limiting factor is something which tends to limit say photosynthesis in a plant .
eg
1. on a bright sunny day the stomata of the leaves close to prevent loss of water. So CO2 acts as a limiting factor as it cannot reach the palisade cells
2.if there is abundant of CO2 but temp is less so the enzymes cannot work sp temp. is a limiting factor
Thanks, but it only limits Photsynthesis does it
-
Thanks, but it only limits Photsynthesis does it
here in this example, yes. But there are other examples as well .. jus remember limiting factor is something which limits the growth of something ..
In the production of penicillin
In the sigmoid curve ( if u remember)
Germination of a seed etc.
-
here in this example, yes. But there are other examples as well .. jus remember limiting factor is something which limits the growth of something ..
In the production of penicillin
In the sigmoid curve ( if u remember)
Germination of a seed etc.
Thank you get :)
-
Please can someone explain the role of hormones in controlling the menstrual cycle (6 marks).
-
Please can someone explain the role of hormones in controlling the menstrual cycle (6 marks).
Menstruation:the lining of the uterus breaks down due to a drop in the level of projesterone and the cells and the blood making up the lining are shed via the vagina:this is menstruation
Under the influence of oestrogen from the ovaries, the linig of the uterus starts to build up agen developing a mass of blood vessels ready to receive a fertilized ovum
FSH causes a follicle in 1 of the ovaries to develop into an ovum
About halfway through the cycle, the level of oestrogen drops, resulting in the secretion of the hormone LH triggerin ovulation.This is when the walls of the ovary ruptures ready to receive a fertilized ovum
The corpus luteum starts 2 secrete projesterone maintainin the uterus lining
at the end of the cycle, the corpus luteum breaks down due to a drop in the level of projesterone, the menstruation occurs agen
u can sum up the functions of the hormones from this description , thts all u need to knw abt the menstrual cycle :D
-
Menstruation:the lining of the uterus breaks down due to a drop in the level of projesterone and the cells and the blood making up the lining are shed via the vagina:this is menstruation
Under the influence of oestrogen from the ovaries, the linig of the uterus starts to build up agen developing a mass of blood vessels ready to receive a fertilized ovum
FSH causes a follicle in 1 of the ovaries to develop into an ovum
About halfway through the cycle, the level of oestrogen drops, resulting in the secretion of the hormone LH triggerin ovulation.This is when the walls of the ovary ruptures ready to receive a fertilized ovum
The corpus luteum starts 2 secrete projesterone maintainin the uterus lining
at the end of the cycle, the corpus luteum breaks down due to a drop in the level of projesterone, the menstruation occurs agen
u can sum up the functions of the hormones from this description , thts all u need to knw abt the menstrual cycle :D
Is the corpus luteum in the ovary?
So oestrogen, progesterone, LH and FSH are all secreated from ovary?
-
This question is hard:
-
Please can someone explain the role of hormones in controlling the menstrual cycle (6 marks).
ok here it goes
OESTROGEN
it is produced in the corpus luteum(follicle). This affects the the pituitary gland to produce FSH ( negative feedback). When FSH is produced it stimulates the ovary to produce an egg. It also helps to build up uterus lining to nourish the embryo if formed
PROGESTERONE
also produced in the follicle. it maintains further nourishment of the uterus lining and controls mucus production to support the embryo. Drop in the levels causes menstruation or break down of lining.
FOLLICLE STIMULATING HORMONE / LUTEINIZING hormone
Follicle-stimulating hormone and Luteinizing hormone are secreted the pituitary gland. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the body.
-
Is the corpus luteum in the ovary?
So oestrogen, progesterone, LH and FSH are all secreated from ovary?
yes corpus is in the ovary ..
oestrogen and progesterone are secreted in the ovary(follicle)
LH and FSH are all secreted in the pituitary gland
-
This question is hard:
OK, thanks, how about that question? that looks hard to me!
-
This question is hard:
Fertility Drugs:: FSH and LH are used in fertility drugs. FSH causes a follicle in one of the ovaries to mature into an ovum. LH causes multiple release of ova.
In males, it increases sperm production
so overall it increases chance of fertilization
Chemical methods of birth control::
Contraceptive pill-> Contains oestrogen and projesterone which prevent ovulation or simply projesterone which prevents implantation of blastula
Condom->Rubber sheath placed on the penis to stop sperm from entering the vagina
-
This question is hard:
umm .. i think i've solved this one for our mock ..
LSH and LH may be used as these drugs ..
they stimulate the production of ovaries to release the eggs and and progesterone and testosterone in males to release sperms ..
oestrogen and progesterone can be used as chemical methods of birth control in the form of pills. They are mixed in specific proportions do that they prevent the release of the egg and the sperm reaching the egg .. also prevent the production of FSH and LH
which year is this ??
-
umm .. i think i've solved this one for our mock ..
LSH and LH may be used as these drugs ..
they stimulate the production of ovaries to release the eggs and and progesterone and testosterone in males to release sperms ..
oestrogen and progesterone can be used as chemical methods of birth control in the form of pills. They are mixed in specific proportions do that they prevent the release of the egg and the sperm reaching the egg .. also prevent the production of FSH and LH
which year is this ??
It's Winter 07
-
Condom->Rubber sheath placed on the penis to stop sperm from entering the vagina
use of condom is physical method brw .. ;)
-
It's Winter 07
lemme check the ms .. ;)
-
By the way, this may sound a dumb question, but is respiration a metabolic reaction. Do all metabolic reactions require oxygen and energy?
-
umm .. i think i've solved this one for our mock ..
LSH and LH may be used as these drugs ..
they stimulate the production of ovaries to release the eggs and and progesterone and testosterone in males to release sperms ..
oestrogen and progesterone can be used as chemical methods of birth control in the form of pills. They are mixed in specific proportions do that they prevent the release of the egg and the sperm reaching the egg .. also prevent the production of FSH and LH
which year is this ??
october 2007
-
lemme check the ms .. ;)
I've looked at the mark scheme and I don't understand it, it talks about hCG - I have no idea what they are! Argh!
-
I've looked at the mark scheme and I don't understand it, it talks about hCG - I have no idea what they are! Argh!
hCG is Human chorionic gonadotropin (not sure abt the spelling).. i jus know tht it is secreted by the embryo after conception ..
yup googled it .. it means the abv .. ;)
-
It's Winter 07
yea saw the ms .. u dont need to worry because u need only 3 points each to score a full ..
-
Also, how to answer w08 last qu. part c) ii), I don't know how to explain it (qu is about ana v ae-robic respiraction)
-
Also, how to answer w08 last qu. part c) ii), I don't know how to explain it (qu is about ana v ae-robic respiraction)
sprint running is basically short distance running so alot of energy is needed for a short time unlike a marathon runner who needs same amount of energy but over a longer time. so a marothon runner needs a good supply of oxygen for his long run while the sprint can use anaerobic respiration because his intake of oxygen will not be needed or normal in this time and he needs lots of energy and also the lactic acid produced will be removed after the race so he will not get pain afterwards.
hope u understoood ..
-
Guys do we have to learn the menstrual cycle??? Hell I hate it.. Its not like it happens with me every month which would've made it easier to remember the steps in it.....
-
Looooool!! Guys are funny with oyr menustrual cycles xd
and why us like eeeveryone sooo hyped on bio?!! I don't do bio bcoz daaamn the syllabus is big etc but.. Yeah seriously cone on bio can't be that hard...? Like my brother did the course accelerated, did it 5 months aaand got an A* and this was in the 1990s! Exams were waay harder then.. Soo you guyss, chill!! :) and good luck y'all! Xxx
-
Looooool!! Guys are funny with oyr menustrual cycles xd
and why us like eeeveryone sooo hyped on bio?!! I don't do bio bcoz daaamn the syllabus is big etc but.. Yeah seriously cone on bio can't be that hard...? Like my brother did the course accelerated, did it 5 months aaand got an A* and this was in the 1990s! Exams were waay harder then.. Soo you guyss, chill!! :) and good luck y'all! Xxx
I totally agree to you with this faaairah bio isn't that hard it's kinda easy..well if you talk about 1990's than your bro would definitely be a genius..heads off to him..:)
-
*censored* Bio! paper 3 was sooo hard! :'(
Anyone, got any notes for Chemistry? I'm doing paper 1 tomorrow...
-
Hey guys!!! On www.freeexampapers.com I can't access Chemistry - 2009 Winter - Paper 1 Variant 2. Can someone give me a link for that paper, which works?
Thanx :D
-
Hey guys!!! On www.freeexampapers.com I can't access Chemistry - 2009 Winter - Paper 1 Variant 2. Can someone give me a link for that paper, which works?
Thanx :D
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Nov/0620_w09_ms_12.pdf
-
bio was so hard...........
anyways how do we study for paper 1 chem. ive gone through all the chapters,should i focus on a specific area?
-
Hey guys!!! On www.freeexampapers.com I can't access Chemistry - 2009 Winter - Paper 1 Variant 2. Can someone give me a link for that paper, which works?
Thanx :D
-
the golden girl: That link ain't working for me. :/
-
~VIN1094~ : Ain't working eitehr. Aaah. Is it the same thing if I do variant 1 for that paper???
-
~VIN1094~ : Ain't working eitehr. Aaah. Is it the same thing if I do variant 1 for that paper???
working fine with me .. are the other papers working .. like 2005 n stuff ?? i think theres a problem with your pdf ..
-
try xtremepapers.net
-
bio ppr was hard...it raped every1..:-/
-
anyone know what was the most component lesson about the exaam tooday 2010
was is the other lesson that didnt come at paper 6 and thats stuff !!?
-
bio ppr was hard...it ****d every1..:-/
r.a.p.e.d ;) :o
-
anyone know what was the most component lesson about the exaam tooday 2010
was is the other lesson that didnt come at paper 6 and thats stuff !!?
i luv to help but it is not allowed...sry
-
okay : )
-
Hello everyone!!! how was bio paper 3?
i mean 'easy' or 'hard'? don't want to reveal anything! ;D
sigh..havent been on9 for a few days! internet problem!
i bet if i logged on the forum more often my grades will go up up up!!!
:D
-
Hello everyone!!! how was bio paper 3?
i mean 'easy' or 'hard'? don't want to reveal anything! ;D
sigh..havent been on9 for a few days! internet problem!
i bet if i logged on the forum more often my grades will go up up up!!!
:D
It was somewhere in the middle for me... :/ u?
-
okay : )
you seem to be new .. have a look here ;)
Rules (https://studentforums.biz/index.php/topic,3515.0.html)
.. By the way WELCOME !! :D :D DO WELL ..
-
It was somewhere in the middle for me... :/ u?
i guess it was harder for me.
i think i screwed up badly at one part of the paper! :-[
but the rest was okay! ;D
cant wait for the 24 hour to end! :D
-
i guess it was harder for me.
i think i screwed up badly at one part of the paper! :-[
but the rest was okay! ;D
cant wait for the 24 hour to end! :D
I messed up randomly... :S but the rest was fine i think.. :)
-
OMG u guys are frightening me -.- :'(
-
OMG u guys are frightening me -.- :'(
Lol, dont worry... relax.. itll be fine.. :)
-
do we hv 2 study only the core stuff 4 chem p1
-
no you i proudly say im gonna faill !!!!!
the exam is after 3 hours :S:S:
-
i guess it was harder for me.
i think i screwed up badly at one part of the paper! :-[
but the rest was okay! ;D
cant wait for the 24 hour to end! :D
LOL HAHAHAHA PART ONE WAS THE FUNNIEST ONE (in a weird way,) ... :P
FLY TIME, FLY!
-
Hey guys, do we have to know Treatment of Sewage for this years portion??? Thanks
-
Hey guys, do we have to know Treatment of Sewage for this years portion??? Thanks
- explain how limited and non-renewable resources can be recycled (including recycling of paper and treatment of sewage to make the water that it contains safe to return to the environment or for human use)
i dont think we need to know HOW it is done ;)
-
- explain how limited and non-renewable resources can be recycled (including recycling of paper and treatment of sewage to make the water that it contains safe to return to the environment or for human use)
i dont think we need to know HOW it is done ;)
coughcoughcough. hahah
-
do we hve 2 study only the core portion 4 chem p1 ???
-
do we hve 2 study only the core portion 4 chem p1 ???
Anything can come so i wouldnt take the chance if i were u.. ;)
-
Stupid school! I'm totally cluless with the Reproduction lesson... We told them we want practicals but they didnt agree -.- >:( ;D ;D ;D ;D
-
Anything can come so i wouldnt take the chance if i were u.. ;)
but ppl who tk core also give p1
-
but ppl who tk core also give p1
dude, m extended and i get lots of mistakes in P1,,, so my guess is u have to know everything. Just study it man ;)
-
but ppl who tk core also give p1
Ohh... well im not sure but if ur doing extended then study everything, if ur doing core then im not really sure.. :S
-
There's this question I can't solve :
Factor that limits photosynthesis when stomata are closed.
The mark scheme says CO2 ...But I don't get it...shouldn't it be light ?
-
Ohh... well im not sure but if ur doing extended then study everything, if ur doing core then im not really sure.. :S
im extended
Thanks
-
but ppl who tk core also give p1
dude why dont u jus do everything .. that will be a good revision for u ;)
-
Stupid school! I'm totally cluless with the Reproduction lesson... We told them we want practicals but they didnt agree -.- >:( ;D ;D ;D ;D
loooool....they'll never let u do practical!!!!
-
There's this question I can't solve :
Factor that limits photosynthesis when stomata are closed.
The mark scheme says CO2 ...But I don't get it...shouldn't it be light ?
No, light is obtained by chloroplasts present on the leaf. CO2 is obtained through the stomata...
-
There's this question I can't solve :
Factor that limits photosynthesis when stomata are closed.
The mark scheme says CO2 ...But I don't get it...shouldn't it be light ?
Ok when the stomata are closed it is impossible for CO2 to reach the leaves for photosynthesis .. so the process "limits" due to CO2
On a cloudy day there is not enough light so no energy to carry out photosynthesis so light "limits" the process
-
loooool....they'll never let u do practical!!!!
Its okay >:( >:( I will do my own experiments in my basement xD ;D ;D :D :D :D
-
dont 4get the video camera!!!!!
-
Hi, sooo..
Water is added to a test-tube containing dilute sulphuric acid of pH 4.
What could be the pH of the resulting solution?
A) 8
B) 6
C) 4
D) 2
i thought the concentration of the acid doesn't change the pH? :/
-
dont 4get the video camera!!!!!
I would like to help students around the world but i think i m gonna keep it to myself this time :D
-
Stupid school! I'm totally cluless with the Reproduction lesson... We told them we want practicals but they didnt agree -.- >:( ;D ;D ;D ;D
LOL XD .. we also told our teacher the same .. they never listen !! n they say students learn better by practical experiments ::) ::) :P jk
-
Oh yeah, how did I forget that ?
It seems like I've begun my pre-exam memory loss :D
Thanks ~VIN1094~ and Raywin :)
-
Hi, sooo..
Water is added to a test-tube containing dilute sulphuric acid of pH 4.
What could be the pH of the resulting solution?
A) 8
B) 6
C) 4
D) 2
i thought the concentration of the acid doesn't change the pH? :/
6 because Water will increase its ph lil bit. It doesnt neutrilise it, just make it bit more. Its like (7+4)/2
-
LOL XD .. we also told our teacher the same .. they never listen !! n they say students learn better by practical experiments ::) ::) :P jk
heheh same here xD we wasted a whole class on trying to convince her ;D ;D
Dude... Our class is like a zoo... all kinds of stuff u can imagine.... Then when this lesson came, believe me man, not a sound ::) :D
-
Oh yeah, how did I forget that ?
It seems like I've begun my pre-exam memory loss :D
Thanks ~VIN1094~ and Raywin :)
No problem.. :) glad to help.. :D
-
Hi, sooo..
Water is added to a test-tube containing dilute sulphuric acid of pH 4.
What could be the pH of the resulting solution?
A) 8
B) 6
C) 4
D) 2
i thought the concentration of the acid doesn't change the pH? :/
no man m sure its B. I remember solving lots of questions like this...
Heyy, yeah, the answer is B, because ur diluting the acid and so its pH increases making it more basic.. :)
-
Oh yeah, how did I forget that ?
It seems like I've begun my pre-exam memory loss :D
Thanks ~VIN1094~ and Raywin :)
BEST OF LUCK !! do it well .. ;) .. like they say .. KILL IT !! :D
-
answer should be C .. water is neutral so it doesnt affect the pH so the pH is not altered
no man m sure its B. I remember solving lots of questions like this...
-
Hi, sooo..
Water is added to a test-tube containing dilute sulphuric acid of pH 4.
What could be the pH of the resulting solution?
A) 8
B) 6
C) 4
D) 2
i thought the concentration of the acid doesn't change the pH? :/
Heyy, yeah, the answer is B, because ur diluting the acid and so its pH increases making it more basic.. :)
-
no man m sure its B. I remember solving lots of questions like this...
oh ok thanks .. :-[
How can crystals be obtained from a hot, concentrated solution of a salt?
A by adding cold water
B by cooling and then filtering
C by filtering only
D by filtering and drying the residue
i know ques stupid .. but i was never taught such stuff :( :(
-
oh ok thanks .. :-[
How can crystals be obtained from a hot, concentrated solution of a salt?
A by adding cold water
B by cooling and then filtering
C by filtering only
D by filtering and drying the residue
i know ques stupid .. but i was never taught such stuff :( :(
B) cooling then filtering :)
think u have to wait for the solution to evaporate a bit then wait for crystals to form. and filter.
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6 because Water will increase its ph lil bit. It doesnt neutrilise it, just make it bit more. Its like (7+4)/2
thaaaaanks
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oh ok thanks .. :-[
How can crystals be obtained from a hot, concentrated solution of a salt?
A by adding cold water
B by cooling and then filtering
C by filtering only
D by filtering and drying the residue
i know ques stupid .. but i was never taught such stuff :( :(
B because crystallization.. :) u have to cool it, wait for crystals to form and then filter.. :)
-
wait... so diluting an acid decreases the pH? :/ or does it only apply to how "strong" and "weak" the acid is?
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B because crystallization.. :) u have to cool it, wait for crystals to form and then filter.. :)
B) cooling then filtering :)
think u have to wait for the solution to evaporate a bit then wait for crystals to form. and filter.
OH YEA !! ITS STILL A SOLUTION !! thank you ! i think i need some sleep ! thanks guys ;)
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wait... so diluting an acid decreases the pH? :/ or does it only apply to how "strong" and "weak" the acid is?
Diluting an acid INCREASES the pH, meaning makes it more basic. This is because its concentration decreases and so it becomes a weaker acid and so its ph changes.. hope u got me.. :P
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Diluting an acid INCREASES the pH, meaning makes it more basic. This is because its concentration decreases and so it becomes a weaker acid and so its ph changes.. hope u got me.. :P
hahaha, ohhh okayy. lol i always thought the pH was only related to how many H+ ions are dissociated, :P XD teheeee; anyways, thanks ;D
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hahaha, ohhh okayy. lol i always thought the pH was only related to how many H+ ions are dissociated, :P XD teheeee; anyways, thanks ;D
Lol.. ;D no problem... :)
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Guys, I'm stressed for Chem P1. Any quick notes? :) Oh and here's an MCQ question:
How are you studying for Chemistry P1?
A. Learning the text book (lol, crazy!)
B. Reading your class notes (takes ages!)
C. Solving question papers (pain in the A**!)
D. Just SFing (fun!)
My take is obviously option D. :P
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queeeeestion.
O/N 03 Chem P1 ; Q9 !
The diagrams show the bonding in three covalent molecules.
1) O-O
2) O-O < DOUBLE BOND
3) O-O < TRIPLE BOND
WHich of these molecules combine to form ammonia?
A) 1 and 2
B) 1 and 3
C) 2 and 3
D) 1,2 and 3
..explanation? D:
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queeeeestion.
O/N 03 Chem P1 ; Q9 !
The diagrams show the bonding in three covalent molecules.
1) O-O
2) O-O < DOUBLE BOND
3) O-O < TRIPLE BOND
WHich of these molecules combine to form ammonia?
A) 1 and 2
B) 1 and 3
C) 2 and 3
D) 1,2 and 3
..explanation? D:
Its easy.. see ammonia is NH3 and before N and H react, N exists as N---N(triple bond) AND H exists as H-H(single bond) so its 1 and 3!!! :P
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Its easy.. see ammonia is NH3 and before N and H react, N exists as N---N(triple bond) AND H exists as H-H(single bond) so its 1 and 3!!! :P
.... why's Nitrogen triple bonded? >P<
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.... why's Nitrogen triple bonded? >P<
Cause its found like tht right? N2 is N---N as each N atom has 5 outer-most electrons... so in a molecule its a triple bond... :)
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Cause its found like tht right? N2 is N---N as each N atom has 5 outer-most electrons... so in a molecule its a triple bond... :)
OH RIGHTTTTT, LOL it has to take.. 3 more electrons , so its triple bonded? :B hahahaha. OKAY, thanks ;D
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OH RIGHTTTTT, LOL it has to take.. 3 more electrons , so its triple bonded? :B hahahaha. OKAY, thanks ;D
Hahaha.. yeah thts it.. :) np.. :D
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jellybeans: Nitrogen atom has 5 electrons in outermost orbit. In order to achieve noble gas status, it requires 3 more electrons. These 3 will come from where? Covalent bonds with other Nitrogen atoms. Thus, Nitrogen is triple-bonded. :)
Am I right, guys? Just gave it a try.
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Awwwh mayn! I type tooo slow. Someone else already gave jellybeans an answer. :-\
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Awwwh mayn! I type tooo slow. Someone else already gave jellybeans an answer. :-\
hahahahaha, like the way you say my name. XD LOL, thanks anyways, :D
-
Can ethene be cracked ?
-
O/N 2003 CHEM P1 , Q36!
Which compound is unsaturated and forms a neutral solution in water?
A) CH2OH-CH--CH-CH2OH
B) CH2OH-CH2-CH2-CH2OH
C) CO2H-CH--CH-CO2H
D) CO2H-CH2-CH2-CO2H
i get the unsaturated bit.. but how do you know if it's neutral or not?
doesnt the 'OH' group make it ... acidic? :B hehs, explanation neeeeeded svp, (X
:P
-
YAYs, jellybeans likes me. xD lol
-
Can ethene be cracked ?
Umm.. i dont think so cause ethene is made by cracking alkanes.
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O/N 2003 CHEM P1 , Q36!
Which compound is unsaturated and forms a neutral solution in water?
A) CH2OH-CH--CH-CH2OH
B) CH2OH-CH2-CH2-CH2OH
C) CO2H-CH--CH-CO2H
D) CO2H-CH2-CH2-CO2H
i get the unsaturated bit.. but how do you know if it's neutral or not?
doesnt the 'OH' group make it ... acidic? :B hehs, explanation neeeeeded svp, (X
:P
answer is A .. why because C doesnt make sense to me ! also OH is alcohol and COOH is acid
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answer is A .. why because C doesnt make sense to me ! also OH is alcohol and COOH is acid
looooool - uhh but howd you know that alcohols can form neutral solutions in water? :(
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looooool - uhh but howd you know that alcohols can form neutral solutions in water? :(
It is supposed to be neutral .. in fact red litmus paper has an ingredient called "alcohol" .. thts a long story now .. google it if u wanna
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It is supposed to be neutral .. in fact red litmus paper has an ingredient called "alcohol" .. thts a long story now .. google it if u wanna
mkay (:thanks.
-
D: sry another one.. how'd you find out the starting volume??
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D: sry another one.. how'd you find out the starting volume??
20% of X (where x is original vol.) = 30 cm^3
30/0.2 = X = 150 cm^3
We use 20% since oxygen is 20% of air and O2 will have reacted with copper.
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20% of X (where x is original vol.) = 30 cm^3
30/0.2 = X = 150 cm^3
We use 20% since oxygen is 20% of air and O2 will have reacted with copper.
THAAAAAAANK YOU! ;D
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D: sry another one.. how'd you find out the starting volume??
Ari answered it, just for the info. Clean air will contain approx. 80% nitrogen and 20% oxygen..
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Ari answered it, just for the info. Clean air will contain approx. 80% nitrogen and 20% oxygen..
mhmm, thanks :)
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Heyy can anyone please explain why the answer is A.
Nov 2004. Chem Ppr 1
33) Which statement explains why iron is used as the catalyst in the manufacture of ammonia?
A) More Ammonia is produced in a given time.
B) The catalyst is unchanged at the end of the reaction.
C) The catalyst neutralises the ammonia.
D) The purity of the Ammonia is improved.
I thght catalyts only speed up the reaction, not increase the yield. Or am I understanding the question incorrectly?
Thanks in advance :)
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Heyy can anyone please explain why the answer is A.
Nov 2004. Chem Ppr 1
33) Which statement explains why iron is used as the catalyst in the manufacture of ammonia?
A) More Ammonia is produced in a given time.
B) The catalyst is unchanged at the end of the reaction.
C) The catalyst neutralises the ammonia.
D) The purity of the Ammonia is improved.
I thght catalyts only speed up the reaction, not increase the yield. Or am I understanding the question incorrectly?
Thanks in advance :)
when they speed the reaction this means more product produced hence increase the yield
i think it's A idk ??? i solved it but i forgot ::)
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when they speed the reaction this means more product produced hence increase the yield
i think it's A idk ??? i solved it but i forgot ::)
yep its A.
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Heyy can anyone please explain why the answer is A.
Nov 2004. Chem Ppr 1
33) Which statement explains why iron is used as the catalyst in the manufacture of ammonia?
A) More Ammonia is produced in a given time.
B) The catalyst is unchanged at the end of the reaction.
C) The catalyst neutralises the ammonia.
D) The purity of the Ammonia is improved.
I thght catalyts only speed up the reaction, not increase the yield. Or am I understanding the question incorrectly?
Thanks in advance :)
If reaction is speeded up it means that more ammonia can be produced in a set amount of time.Like if you run instead of walk then you naturally cover more distance
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y does nov 2009 paper 1 variant 2 ......is said accountin when i open the page ???
i even triedd xtrem papers but it's the same over there too
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do hv to study organic chemistry for p1
(I hate organic chem)
-
do hv to study organic chemistry for p1
(I hate organic chem)
yes the basics . .last 2-3 questions are based on them ..
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thenewkid:
http://www.cambridgestudents.org.uk/subjectpages/chemistry/igcsechemistry/FinalChemChemistrychecklist%20Version%20CW.pdf
There's your answer. :)
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By the way, guys. Chem P1 is only Core syllabus! Rejoice!~ :D
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any tips for chem p1 2morow???i have 2 papers 2morow and have no time to revise all chem :'(....
pls help...
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any tips for chem p1 2morow???i have 2 papers 2morow and have no time to revise all chem :'(....
pls help...
I got chem p1 AND french p2.. :'( just do past papers and and doubt then learn tht part.. :)
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any tips for chem p1 2morow???i have 2 papers 2morow and have no time to revise all chem :'(....
pls help...
The best thing to do before a MCQ paper is --> Get a notebook, make an answer table from 1-40 for each question. Open papers (soft-copy) from 2002, and do the 2002-2009 all night.
In the end, check the answers, mark yourself, and I guarantee , you'll see a hell lotta similar questions popping up in the paper 2morrow.
If u have already done this, sleep well, thats all you need.
-
The best thing to do before a MCQ paper is --> Get a notebook, make an answer table from 1-40 for each question. Open papers (soft-copy) from 2002, and do the 2002-2009 all night.
In the end, check the answers, mark yourself, and I guarantee , you'll a hell lotta similar questions popping up in the paper 2morrow.
If u have already done this, sleep well, thats all you need.
You make me feel a WHOLE lot better.. :D
-
thenewkid:
http://www.cambridgestudents.org.uk/subjectpages/chemistry/igcsechemistry/FinalChemChemistrychecklist%20Version%20CW.pdf
There's your answer. :)
Thanks
-
luv3life: OMG, Is that true? So I only study from the core??
Wait a sec, it is true, stupid me for never thinking about it....
-
If you have done what A@di said (LIKE ME ;D) then do the OLD PAPERS from 1993
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If you have done what A@di said (LIKE ME ;D) then do the OLD PAPERS from 1993
I have done all the papers from 2002 onwards... like A@di said but im worried whether the multiple choice will be asked in a different way.. :S I mean aft bio im just freaked out abt the entire format... :P
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Nov 2009
Atom X has 8 more electrons than atom Y.
Student 1 says they are in the same group.
Student 2 says they are unreactive.
Which students can be correct?
student 1 student 2
A tick tick
B tick cross
C cross tick
D cross cross
Answer is A. HOW COME? ??? :-\
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i need help in the followin :
in june 2006 chem paper 1 , i don't undertans y Q 35 is c (y does the OH bond no.1 not included in the answer ???)
ohh and also same year question 15 ...... isn't the reaction exothermic , so y temp has to increase ???
thx in a advance
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Exothermice mean energy (heat) given out leading to a temp. rise.
Opposite true for Ednothermic.
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Exothermice mean energy (heat) given out leading to a temp. rise.
Opposite true for Ednothermic.
i actually referred my ans to the equilibrium lesson ....whne temp increases , the reaction's decreases
so y my referring thing is wrong ....y in this case i got to refer to urs .....when do i refer to my thiny and when do i refer to urs ???
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Nov 2009
Atom X has 8 more electrons than atom Y.
Student 1 says they are in the same group.
Student 2 says they are unreactive.
Which students can be correct?
student 1 student 2
A tick tick
B tick cross
C cross tick
D cross cross
Answer is A. HOW COME? ??? :-\
each full outer shell has 8 electrons .. and.. if it was in group one, Li has 3 electrons, plus 8, you get 11. and you add another 8 electrons, you get 19. there's always 1 electron left on the outermost shell. (which shows that they're in the same group) so your answer must be A or B..
then, they 'can' be unreactive as well , cuz for noble gases, Neon has 10 electrons. Plus 8, you get 18 (Ar). plus another 8, 36 (Kr). and there's always gonna be a full outermost shell... (which shows that they're unreactive), so... yeah both students can be right, :P & its tick for student 1 & 2 so its A.
:)
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Good Bye, people. I'm gona do past papers all night now. Then sleep. Got an exam in less than 12 hours. :P
Alll the Best for whatever exam you do, especially Chemistry Paper 1. :)
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i actually referred my ans to the equilibrium lesson ....whne temp increases , the reaction's decreases
so y my referring thing is wrong ....y in this case i got to refer to urs .....when do i refer to my thiny and when do i refer to urs ???
for question 15
Dont confuse rates of reactions and equilibrium.
Think about it like this, if I heat you up to 4000 degrees centigrade you will start SHOOTING AROUND THE ROOM.
Thus you collide more often with other atoms and the rate of the reaction increases. Thus answer is D
-------------------------------------------------------------------------------------------------------------------------------------
For equilibrium reactions the RATE of the FORWARD reaction is reduced by a temperature rise.
-
Can anyone list down all the colours of Metals, non-metals, gases and everything else that's included in the syllabus for Paper 1? (Including Hydroxide, etc..) There are a lot of questions about it especially in electrolysis.
-
for question 15
Dont confuse rates of reactions and equilibrium.
Think about it like this, if I heat you up to 4000 degrees centigrade you will start SHOOTING AROUND THE ROOM.
Thus you collide more often with other atoms and the rate of the reaction increases. Thus answer is D
-------------------------------------------------------------------------------------------------------------------------------------
For equilibrium reactions the RATE of the FORWARD reaction is reduced by a temperature rise.
[/quotokay now i get it ..can u plz answer Q35 in same year :-[
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i need help in the followin :
in june 2006 chem paper 1 , i don't undertans y Q 35 is c (y does the OH bond no.1 not included in the answer ???)
ohh and also same year question 15 ...... isn't the reaction exothermic , so y temp has to increase ???
thx in a advance
ok here ..
H OH H Na
| / | /
H- C - C=O + NaOH ----> H-C- C = O + H2O
| |
H H
This is a simplified reaction showing ethanoic acid reacting with sodium hydroxide to give Sodium ethanoate (salt) and water
in your ques only (2) can be displaced or only that -OH can be displaced
like for eg in HCOOH only the bold H can be displaced
-
Can anyone list down all the colours of Metals, non-metals, gases and everything else that's included in the syllabus for Paper 1?
all gases r colourless ....except for Nitrogen dioxide which is brown
as for metals , metals in group one and two are all grey .........transition metals too except for gold which it's colour os golden lik me :P ..anyways and there is copper that is brown ....adn what else ::) ...um that's all ..ohh mercury is silver but it's in liquid form
as for non-metals ....group 7 (halogens) .....F is yeelo , Cl is green ,Br is brown , I is grey ,and Astatine thingy is Black ..... that's all i kno
hope i helped ::)
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ok here ..
H OH H Na
| / | /
H- C - C=O + NaOH ----> H-C- C = O + H2O
| |
H H
This is a simplified reaction showing ethanoic acid reacting with sodium hydroxide to give Sodium ethanoate (salt) and water
in your ques only (2) can be displaced or only that -OH can be displaced
like for eg in HCOOH only the bold H can be displaced
aha now i get ,thx mate :D
-
^^Thanks but I think you missed some.
also,
Can anyone list down all the colours of Metals, non-metals, gases and everything else that's included in the syllabus for Paper 1? (Including Hydroxide, etc..) There are a lot of questions about it especially in electrolysis.
So how do we know the colour of hydroxides and the other stuff?
Check Oct/Nov 2009 P1 Q13, They say that OH- makes the UI colourless. Why?
-
The best thing to do before a MCQ paper is --> Get a notebook, make an answer table from 1-40 for each question. Open papers (soft-copy) from 2002, and do the 2002-2009 all night.
In the end, check the answers, mark yourself, and I guarantee , you'll see a hell lotta similar questions popping up in the paper 2morrow.
If u have already done this, sleep well, thats all you need.
thanks!!!u calmed me....
-
y do we need to dry gas??sometimes they pass a gas through sulfuric acid to dry it. y??
-
plz answer my folowin Q
in june 2007 ,Q11 , y the no. of atome is 8 y not 9 ???
oh and in Q 3 same year , y it is 75.5 not 84.5 ??? ???
plz help
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y do we need to dry gas??sometimes they pass a gas through sulfuric acid to dry it. y??
see if this helps u ..
http://www.chem.ucalgary.ca/courses/351/laboratory/drying%20agents.pdf
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plz answer my folowin Q
in june 2007 ,Q11 , y the no. of atome is 8 y not 9 ???
oh and in Q 3 same year , y it is 75.5 not 84.5 ??? ???
plz help
ethanoic acid - CH3COOH count them they are eight
Q3 if u look at the scale of the therm. it has 10 divisions for 5 *C and the mercury is showing something5.5 .. i'll show u on the diag. itself gimme 1 min
HAS IT BECOME TOO COMPLICATED ??
-
plz answer my folowin Q
in june 2007 ,Q11 , y the no. of atome is 8 y not 9 ???
oh and in Q 3 same year , y it is 75.5 not 84.5 ??? ???
plz help
q3) each small division is 0.5 (there r 20 divisions between 2 big lines...so 10/20=0.5)
the mercury is at 5.5
so it cant be 84.5
q11) ethanoic acid -- ch3cooh
2 carbon + 4 hydrogen + 2 oxygen
total=2+4+2=8
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plz answer my folowin Q
in june 2007 ,Q11 , y the no. of atome is 8 y not 9 ???
oh and in Q 3 same year , y it is 75.5 not 84.5 ??? ???
plz help
CH3COOH - 1+3+4 = 8
2Cs, 4H, 2O
ok check vin's post, better explanation
-
QUESTION!
i thought you get CaO + CO2 from heating Lime? :( :(
help..?
-
QUESTION!
i thought you get CaO + CO2 from heating Lime? :( :(
You get CaO and CO2 from heating Calcium Carbonate, not lime
Lime = CaO
Calcium Carbonate = CaCO3
-
You get CaO and CO2 from heating Calcium Carbonate, not lime
Lime = CaO
Calcium Carbonate = CaCO3
OHHHHH, THANKS!
-
see if this helps u ..
http://www.chem.ucalgary.ca/courses/351/laboratory/drying%20agents.pdf
thx.it does help me.... 8)
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OHHHHH, THANKS!
Anytime.
-
A@di i stil didn't get Q 3 :-[ :-[
i kno i'm askin alot but plz help lol
i also have this
same year Q16 :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[
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A@di i stil didn't get Q 3 :-[ :-[
do you get this ??
https://studentforums.biz/index.php/topic,1411.msg221498.html#msg221498
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thx.it does help me.... 8)
ok ur welcome ;)
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this drove me crazy during my IGCSEs too..
S + 02 --> S02
S - oxidation number 0..
O2 - oxidation number 0
SO2 --> oxidation number of O = (-2*2) = -4 , thus oxidation number of S = +4
S--> 0 to 4 oxidation
O -> 0 to -4 reduction
thus redox.
2S02 + 02-->2 S03
2SO2 -> oxidation number of O = (-2*2) = -4, thus S = +4. O2 -> 0, final of O = -4+0 = -4
SO3--> Oxidation number of O = (-2*3) = -6, of S = +6
Final , S --> 4 to 6 oxidation
O --> -4 to -6 reduction
SO3 + H20--> H2SO4
SO3 --> O = (-3*2) = -6 , thus S = +6
H2O --> O = -2, thus H = +2
O in both compounds thus, final number of O = -6-2 = -8
H2SO4--> O = (-2*4) = -8, thus H = +2, as final oxidation number of the compound shud be 0, -8+2+S = 0
thus, S = +6
now the changes
S --> 6 to 6
H --> 2 to 2
O --> -8 to -8..
NOt redox.
-
Redox reactions, or oxidation-reduction reactions, have a number of similarities to acid-base reactions. Redox reactions are concerned with the transfer of electrons between species. Like acid-base reactions, redox reactions are a matched set -- you don't have an oxidation reaction without a reduction reaction happening at the same time. Oxidation refers to the loss of electrons, while reduction refers to the gain of electrons.
OIL RIG
oxidation is loss of electrons
reduction is the gain of electrons
@Aadi .. i was looking for this one u've posted .. as usual u got me ;)
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@Aadi .. i was looking for this one .. as usual u got me ;)
lol its k, she has to understand the oxidation/reduction numbers too...that concept is very important..
-
ummmmm.. :/ lol how are we supposed to solve that question? :p
-
each full outer shell has 8 electrons .. and.. if it was in group one, Li has 3 electrons, plus 8, you get 11. and you add another 8 electrons, you get 19. there's always 1 electron left on the outermost shell. (which shows that they're in the same group) so your answer must be A or B..
then, they 'can' be unreactive as well , cuz for noble gases, Neon has 10 electrons. Plus 8, you get 18 (Ar). plus another 8, 36 (Kr). and there's always gonna be a full outermost shell... (which shows that they're unreactive), so... yeah both students can be right, :P & its tick for student 1 & 2 so its A.
:)
Thanks. :) But I still don't get it. I mean, it could be ANY two elements :S, how can we predict they're unreactive :( Any ideas anyone? Nov 2009. Q4
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ummmmm.. :/ lol how are we supposed to solve that question? :p
LOLS! Which paper and year was it?
-
this drove me crazy during my IGCSEs too..
S + 02 --> S02
S - oxidation number 0..
O2 - oxidation number 0
SO2 --> oxidation number of O = (-2*2) = -4 , thus oxidation number of S = +4
S--> 0 to 4 oxidation
O -> 0 to -4 reduction
thus redox.
2S02 + 02-->2 S03
2SO2 -> oxidation number of O = (-2*2) = -4, thus S = +4. O2 -> 0, final of O = -4+0 = -4
SO3--> Oxidation number of O = (-2*3) = -6, of S = +6
Final , S --> 4 to 6 oxidation
O --> -4 to -6 reduction
SO3 + H20--> H2SO4
SO3 --> O = (-3*2) = -6 , thus S = +6
H2O --> O = -2, thus H = +2
O in both compounds thus, final number of O = -6-2 = -8
H2SO4--> O = (-2*4) = -8, thus H = +2, as final oxidation number of the compound shud be 0, -8+2+S = 0
thus, S = +6
now the changes
S --> 6 to 6
H --> 2 to 2
O --> -8 to -8..
NOt redox.
i read it like 4 times lol :-[ thx mate
-
By the way another Q (defenityl getin my butt kicked today :-X)
same year Q 18 :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[
-
No comment on today's paper. :/
-
ummmmm.. :/ lol how are we supposed to solve that question? :p
study .. dont waste your time :P
-
No comment on today's paper. :/
Keep it that way for 24 Hours ;) ;D
-
2days ppr ws more like Environmental management than bio
-
By the way another Q (defenityl getin my butt kicked today :-X)
same year Q 18 :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[
this is test for zinc anion .. SOLUBLE in excess for both is the ans A ??
-
this is test for zinc anion .. SOLUBLE in excess for both is the ans A ??
ya it is and i don't get it ???
-
THIS IS A GENERAL NOTICE TO ALL USERS:
PLEASE REFRAIN FROM DISCUSSING EXAM DETAILS UNTIL 24 HOURS HAVE PASSED
-
I hope someone can still answer my doubt.
Can anyone list down all the colours of Metals, non-metals, gases and everything else that's included in the syllabus for Paper 1? (Including Hydroxide, etc..) There are a lot of questions about it especially in electrolysis. Plus the oxides of metals
-
THIS IS A GENERAL NOTICE TO ALL USERS:
PLEASE REFRAIN FROM DISCUSSING EXAM DETAILS UNTIL 24 HOURS HAVE PASSED
yo ari u saw my message?
By the way guys: When is hydrogen produced from cracking?
-
study .. dont waste your time :P
hahaha, i've.. already studied but.. OKAY, lol i'm still gona do more pastyears first... :B ;D ;D ;D
-
ya it is and i don't get it ???
You might have .. u should have done this for paper 6 :-\
-
I hope someone can still answer my doubt.
Can anyone list down all the colours of Metals, non-metals, gases and everything else that's included in the syllabus for Paper 1? (Including Hydroxide, etc..) There are a lot of questions about it especially in electrolysis. Plus the oxides of metals
Bromine: brown
Chlorine: green
Iodine: grey
lead: silver
-
You might have .. u should have done this for paper 6 :-\
VIN thx , i don't kno what the heck is wrong with me today >:(......
thx for baring with me (that's what our supervisor says whenever sh e reads the rules and regulations of ig exam ...so hilarious , i keep laughin with my self most of the time she's readi cuz i memorixed it people :P)
-
since when did metals react with bases?
asnwr is B
-
LOLS! Which paper and year was it?
XD hahaha.. it's M/J 06 Physics P1 :P
there are almost.. 5 blank questions :P
-
yo ari u saw my message?
By the way guys: When is hydrogen produced from cracking?
H H H H
| | (steam) | |
H- C - C - H ----------> C = C + H2
| | (>800 *C) | |
H H H H
ETHANE ETHENE HYDROGEN ;)
-
since when did metals react with bases?
asnwr is B
lol this has nothing to do with metals reacting with bases? ...
-
Baladya: I know those simple stuff, I'm more concerned about the oxides of metals and Hydroxide...
Anyone?
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VIN thx , i don't kno what the heck is wrong with me today >:(......
thx for baring with me (that's what our supervisor says whenever sh e reads the rules and regulations of ig exam ...so hilarious , i keep laughin with my self most of the time she's readi cuz i memorixed it people :P)
LOL .. it happens .. i know .. @your supervisor .. i wanna hear her ! :P
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this drove me crazy during my IGCSEs too..
S + 02 --> S02
S - oxidation number 0..
O2 - oxidation number 0
SO2 --> oxidation number of O = (-2*2) = -4 , thus oxidation number of S = +4
S--> 0 to 4 oxidation
O -> 0 to -4 reduction
thus redox.
2S02 + 02-->2 S03
2SO2 -> oxidation number of O = (-2*2) = -4, thus S = +4. O2 -> 0, final of O = -4+0 = -4
SO3--> Oxidation number of O = (-2*3) = -6, of S = +6
Final , S --> 4 to 6 oxidation
O --> -4 to -6 reduction
SO3 + H20--> H2SO4
SO3 --> O = (-3*2) = -6 , thus S = +6
H2O --> O = -2, thus H = +2
O in both compounds thus, final number of O = -6-2 = -8
H2SO4--> O = (-2*4) = -8, thus H = +2, as final oxidation number of the compound shud be 0, -8+2+S = 0
thus, S = +6
now the changes
S --> 6 to 6
H --> 2 to 2
O --> -8 to -8..
NOt redox.
Can anyone please explain this, I don't get this at all. What's oxidation number?
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H H H H
| | (steam) | |
H- C - C - H ----------> C = C + H2
| | (>800 *C) | |
H H H H
ETHANE ETHENE HYDROGEN ;)
VIN , plz look again at what u wrote ...ur talkin abt hydration ....while baladya is talkin abt crackin
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Baladya: I know those simple stuff, I'm more concerned about the oxides of metals and Hydroxide...
Anyone?
i had the same porb , but u gotta do is that u memorized the solubility thingy list AND memorize the reactivity series ...ohh and understand them
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lol this has nothing to do with metals reacting with bases? ...
i copied the wrong question
opsi daizy
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Oxides and hydroxides..ummm, ok one thing to remember, learn the few basic colors of transition metals, like Fe(II)/Fe(iii) brown green stuff.
For example, nickel compounds are green, nickel being a transition metal.
Nickel hydroxide is also green...so u know wat im talking abt rite??
learn the colors of the metal compounds ...
copper - blue
iron - green /brown..etc. check the identification of cations table.
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Umm, link to O/N 2009 P1 please? :)
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Nov/0620_w09_qp_11.pdf
I don't understand Q23, why have they chosen 2 and 3 only? And Q13 why does OH- turn UI colourless?
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LOL .. it happens .. i know .. @your supervisor .. i wanna hear her ! :P
lol ....trust u do :P
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VIN , plz look again at what u wrote ...ur talkin abt hydration ....while baladya is talkin abt crackin
Ethane --> Ethene + Hydrogen
Cracking.
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VIN, but when do we know if h2 is coming out and when do we know an alkene is coming out?
-
i copied the wrong question
opsi daizy
hahahaha.. isn't that a displacement reaction? :P lol, ><
metal X displaces Y cuz its more reactive..? no? :/
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Nov/0620_w09_qp_11.pdf
I don't understand Q23, why have they chosen 2 and 3 only?
copper is below hydrogen in the reactivity series ...it can't displace Hydrogen ..therefore ..no reaction ..hence 2 and 3 only ;)
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Ethane --> Ethene + Hydrogen
Cracking.
Octane ---> Hexane + ethene
Thats what the book says... so when is it an alkene and when hydrogen?
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H H H H
| | (steam) | |
H- C - C - H ----------> C = C + H2
| | (>800 *C) | |
H H H H
ETHANE ETHENE HYDROGEN ;)
VIN , plz look again at what u wrote ...ur talkin abt hydration ....while baladya is talkin abt crackin
Nop .. im 100% sure .. ethane cracks to give ethene and hydrogen .. which IS cracking
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Octane ---> Hexane + ethene
Thats what the book says... so when is it an alkene and when hydrogen?
H H H H
| | (steam) | |
H- C - C - H ----------> C = C + H2
| | (>800 *C) | |
H H H H
ETHANE ETHENE HYDROGEN ;)
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hahahaha.. isn't that a displacement reaction? :P lol, ><
metal X displaces Y cuz its more reactive..? no? :/
BOTH ARE METALS !!
METAL OXIDE IS A BASE
METALS DONT REACT WITH METAL OXIDE :/
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i copied the wrong question
opsi daizy
B?
@baladya - Hydrogen from cracking, erm. Ethane --> Ethene + Hydrogen , this is the only way ..
one more , but no hydrogen, cracking though
Decane --> pentane + ethene + propene
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@the golden girl: Right, thanks for the answer, what about Q13, why is the UI colourless for OH-?
-
ethanoic acid - CH3COOH count them they are eight
Q3 if u look at the scale of the therm. it has 10 divisions for 5 *C and the mercury is showing something5.5 .. i'll show u on the diag. itself gimme 1 min
HAS IT BECOME TOO COMPLICATED ??
oK GUYS I really DONT GET THE q3 THE thermometer one... :S PLEASE help... :(
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BOTH ARE METALS !!
METAL OXIDE IS A BASE
METALS DONT REACT WITH METAL OXIDE :/
huh??
Another example of 'competition' between metals to form compounds is observed in the reaction between metals and metal oxides.
Observe the reaction between iron and copper oxide, mixed and heated strongly.
http://www.s-cool.co.uk/gcse/chemistry/metals--the-reactivity-series/displacement-reactions-and-the-reactivity-series.html
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VIN, but when do we know if h2 is coming out and when do we know an alkene is coming out?
depends on the alkane .. actually in only the one i hav mentioned.. hydrogen "comes out " :P
-
Do they provide us with the reactivity series list in chemistry paper 1 igcse?
-
B?
@baladya - Hydrogen from cracking, erm. Ethane --> Ethene + Hydrogen , this is the only way ..
one more , but no hydrogen, cracking though
Decane --> pentane + ethene + propene
I think i understand whats wrong...
When its craking of things like Ethane, hydrogen is gonna be the product
When its cracking of Octane, Decane, bla bla its alkene that is the product
-
B?
@baladya - Hydrogen from cracking, erm. Ethane --> Ethene + Hydrogen , this is the only way ..
one more , but no hydrogen, cracking though
Decane --> pentane + ethene + propene
yeah
have u ever seen A BASE REACT WITH METAL? nop
anyway probably it was heated..but that was the only logic asnwer
displacemet reaction can occur with salts yes i kno
but im not sure with metal oxdie and another metal
-
Do they provide us with the reactivity series list in chemistry paper 1 igcse?
No they dont.
-
Octane ---> Hexane + ethene
Thats what the book says... so when is it an alkene and when hydrogen?
isma3 hwa 3ala hasab il su2al ,k!
meaning : ...if they give u an alkAne --> alkAne ,then there is alkEne with it
and if they give u an alkAne --. alkEne then there is hydrogen with it
;)
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BOTH ARE METALS !!
METAL OXIDE IS A BASE
METALS DONT REACT WITH METAL OXIDE :/
yeah
but metal oxide dont react with metal?
OBVIOUSLY THEY CAN ! if the reacting metal is more reactive
6Na + Al2O3 ----> 3Na2O + 2Al
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Do they provide us with the reactivity series list in chemistry paper 1 igcse?
nope, remember it this way.
popular scientist can make a zoo in the low humidity countryside more satisfactory.Goodbye.
potassium
sodium
calcium
magnesium
aluminium
zinc
iron
tin
lead
hydrogen
copper
mercury
silver
gold
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Do they provide us with the reactivity series list in chemistry paper 1 igcse?
I am afraid not .. :( then what would have been the point of testing us ? :P
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isma3 hwa 3ala hasab il su2al ,k!
meaning : ...if they give u an alkAne --> alkAne ,then there is alkEne with it
and if they give u an alkAne --. alkEne then there is hydrogen with it
;)
I think ur right
-
No they dont.
uh-oh...i'm doomed :'(
Thanks.
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oh ok cheers i got It !
-
nope, remember it this way.
popular scientist can make a zoo in the low humidity countryside more satisfactory.Goodbye.
potassium
sodium
calcium
magnesium
aluminium
zinc
iron
tin
lead
hydrogen
copper
mercury
silver
gold
LOL ... XD LMAO !!! :D :D !! AWESOME !! XD LMAO !! thanks man .. u saved us !
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i need help with nov 2009 paper 1 first variant numbers 13,15 and 28.
http://www.freeexampapers.com/FreeExamPapers.com_.php?__lo=SUdDU0UvQ2hlbWlzdHJ5L0NJRS8yMDA5IE5vdi8wNjIwX3cwOV9xcF8xMS5wZGY=
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LOL ... XD LMAO !!! :D :D !! AWESOME !! XD LMAO !! thanks man .. u saved us !
LOL, this was posted by some1 long long time ago..
here there are more
THIS IS VERY IMPORTANT FOR ELECTROLYSIS, AS IN WHICH CATION/ANION GOES TO THE ELECTRODE FIRST
for cations reactivity series:
please-K
send-Na
cats-Ca
monkeys-Mg
and-Al
zebras-Zn
in-iron
large-lead
hired-H
cages-Cu
make-Hg
sure-Ag
padlocked-platinum
for anions:
someone -sulphate
nice-nitrate
only-hydroxide(gives oxygen on oxidation)
cleans-chloride
broken -bromide
items-iodide
-----------
the lower ones break free/move to the electrode first, in both the cases.
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lol tommorow m gonna get totally screwed in the molles question >.< ;D ;D ;D
Edit: O wait... TOMMOROW IS PAPER 1 NO MOLLES OMG YESSSSSSSSSS ;D ;D ;D ;D ;D
Lol thank goddd. I m gonna spend the 10 days holiday doing molles xD
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@the golden girl: Right, thanks for the answer, what about Q13, why is the UI colourless for OH-?
guys help ???
-
guys help ???
what is the universal indicator?
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A@di i stil didn't get Q 3 :-[ :-[
i kno i'm askin alot but plz help lol
i also have this
same year Q16 :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[
Same here!! I dont get it!! :(
-
tricky question
ASNWER IS D
why?
-
what is the universal indicator?
i think it is meant to be a litmus paper ???
A@di or VIN anyone help us ???
-
Oct/Nov 2009 P1
Q13, why is the UI colourless for OH-?
Also
I don't understand Q26....
God, it all about the colours, can't anyone give me the rules of colours? I think everyone really needs that...
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tricky question
ASNWER IS D
why?
it says explotion... so what happens is a VERY fast reaction. Very fast that finishes very fast ;)
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i gotta think about that universal indicator too. the others are here
15) hydrogen , it doesnt emit CO2, rest do , uranium doesnt need O2
28) Copper - brown solid
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Oct/Nov 2009 P1
Also
I don't understand Q26....
God, it all about the colours, can't anyone give me the rules of colours? I think everyone really needs that...
compounds of transition metals are colored. cud be B(white) or C (red)
they are metals thus their electrical conductivity is high. so C
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well i know wat universal indicator is, it displays a range of colors when put in acid or alkali. blue/purple for alkali, red orange for acid. green for neutral. google it. and im still thinking abt that q..ill PM ari and nid.
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i think it is meant to be a litmus paper ???
A@di or VIN anyone help us ???
WAIT I HAV POSTED THIS ONE EARLIER THIS DAY !!.. LEMME CHECK !! :D
-
Can u tell me any 'weird' monemers we need to know ... (stuff like Acrylonitrile 0.o )
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it says explotion... so what happens is a VERY fast reaction. Very fast that finishes very fast ;)
yes, correct. Hydrogen combustion happens extremely fast..its like BOOM!! lol....and once its finished, the speed of reaxn drops!
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it says explotion... so what happens is a VERY fast reaction. Very fast that finishes very fast ;)
hmm thanks !
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compounds of transition metals are colored. cud be B(white) or C (red)
they are metals thus their electrical conductivity is high. so C
Thanks, what about Q13??
-
heyyyyy,does anybody know where i can get CHEM O/N 06 paper without the blank questions? X(
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i think it is meant to be a litmus paper ???
A@di or VIN anyone help us ???
https://studentforums.biz/index.php/topic,8110.msg220546.html#msg220546
https://studentforums.biz/index.php/topic,8110.msg220698.html#msg220698
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heyyyyy,does anybody know where i can get CHEM O/N 06 paper without the blank questions? X(
I dunno wat blank ques r u talking abt
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heyyyyy,does anybody know where i can get CHEM O/N 06 paper without the blank questions? X(
lol wtf is that xD ;D ;D
-
ok u have to go with colorless, because Chlorine is not acidic or basic. the only option with colorless...
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Thanks, what about Q13??
Ok remember when concentrated NaCl is electrolyzed:
First the solution contains Na+ Cl- and H+ and OH- (from water). The positive inos go to the cathode, and negative ions to the anode.
At the CATHODE
the H+ ions accept electrons, since it is less reactive than Na (always elements which is more reactive 'likes' to stay in the ionic form)
2H+ + 2e- ---> H2
At the ANODE
the Cl- ions give up the electrons more readily than the OH- ions do.
2Cl- --> Cl2 + 2e-
what left in the solution is Na+ and OH- which combine to form NaOH
in your ques ..is 'D' .. the indicator solution turns blue at -ve as NaOH is produced .. Chlorine doesnt show any change in presence of an indicator solution ;)
jus understand the concept ..
(http://content.answers.com/main/content/img/McGrawHill/Encyclopedia/images/CE221700FG0010.gif)
see in this question u hav to act smart .. look at the options .. u now kno tht NaOH is produced so the indicator turns blue ..there are two options with 'bule/purple' A and B .. now see A .. at -ve 'red' is given which is not possible because no acid it produced during the reaction so u r left with D .. ;)
-
Ok remember when concentrated NaCl is electrolyzed:
First the solution contains Na+ Cl- and H+ and OH- (from water). The positive inos go to the cathode, and negative ions to the anode.
At the CATHODE
the H+ ions accept electrons, since it is less reactive than Na (always elements which is more reactive 'likes' to stay in the ionic form)
2H+ + 2e- ---> H2
At the ANODE
the Cl- ions give up the electrons more readily than the OH- ions do.
2Cl- --> Cl2 + 2e-
what left in the solution is Na+ and OH- which combine to form NaOH
in your ques ..is 'D' .. the indicator solution turns blue at -ve as NaOH is produced .. Chlorine doesnt show any change in presence of an indicator solution ;)
jus understand the concept ..
(http://content.answers.com/main/content/img/McGrawHill/Encyclopedia/images/CE221700FG0010.gif)
see in this question u hav to act smart .. look at the options .. u now kno tht NaOH is produced so the indicator turns blue ..there are two options with 'bule/purple' A and B .. now see A .. at -ve 'red' is given which is not possible because no acid it produced during the reaction so u r left with D .. ;)
u said H2 goes to cathode , then y u said sodium hydroxide changes indicator to blue when it is at the bottom not even close to the +ve electrode
-
for anions:
someone -sulphate
only-hydroxide(gives oxygen on oxidation)
nice-nitrate
cleans-chloride
broken -bromide
items-iodide
Are you sure??? I've always come across series that put nitrate above hydroxide.
Plus one final thing people, in June 2000, shouldn't question 30 be C??? (Paper 1 Chemistry)
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I dunno wat blank ques r u talking abt
... there .. blank questions :P
-
u said H2 goes to cathode , then y u said sodium hydroxide changes indicator to blue when it is at the bottom not even close to the +ve electrode
see in this question u hav to act smart .. look at the options .. u now kno tht NaOH is produced so the indicator turns blue ..there are two options with 'bule/purple' A and B .. now see A .. at -ve 'red' is given which is not possible because no acid it produced during the reaction so u r left with D .. ;)
-
So what do u want us to do? Make a new question paper ;D xD :P
-
see in this question u hav to act smart .. look at the options .. u now kno tht NaOH is produced so the indicator turns blue ..there are two options with 'bule/purple' A and B .. now see A .. at -ve 'red' is given which is not possible because no acid it produced during the reaction so u r left with D .. ;)
wait isn't hydrgoen an acidic gas ???
-
Are you sure??? I've always come across series that put nitrate above hydroxide.
Plus one final thing people, in June 2000, shouldn't question 30 be C??? (Paper 1 Chemistry)
OOPS! THANKS, ITS ABOVE HYDROXIDE
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wait isn't hydrgoen an acidic gas ???
http://wiki.answers.com/Q/What_is_an_acidic_hydrogen_atom (http://wiki.answers.com/Q/What_is_an_acidic_hydrogen_atom)
Read this...
-
http://wiki.answers.com/Q/What_is_an_acidic_hydrogen_atom (http://wiki.answers.com/Q/What_is_an_acidic_hydrogen_atom)
Read this...
tayeeb ma it turns to be an ion hence is ACIDIC!!
-
wait isn't hydrgoen an acidic gas ???
yes but it has to dissociate with water to give H+ to show its acidity ..
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tayeeb ma it turns to be an ion hence is ACIDIC!!
I dont know ur question but ur right and VIN is right in ur last posts
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yes but it has to dissociate with water to give H+ to show its acidity ..
VIN (i kno u'll kill me but anyways) .... when does Hydrogen have an ion ....u say dissociate with water ,so is there any other way it get's an ion charge thingy
-
hmmm
isnt this supposed to be MG0 + H2?
MARK SCHEME SAYS A :/
-
hmmm
isnt this supposed to be MG0 + H2?
MARK SCHEME SAYS A :/
are you sure? check the markscheme again..if its steam it should be magnesium oxide + hydrogen
-
yea....it should be MgO + H2
-
VIN (i kno u'll kill me but anyways) .... when does Hydrogen have an ion ....u say dissociate with water ,so is there any other way it get's an ion charge thingy
its ok its good to ask ques .. listen hydrogen has an ion when it is bound with a cation meaning when it is in an acid form .. eg HCl .. when HCl disassociates in water is gives out H+ ion .. this ion is very unstable so it combines with H2O .. to give H3O+ .. u see that PLUS over H3O ?? tht is very IMPORTANT it is called hydronium ion .. the concentration of THIS "ION" .. i repeat ION !! very imp because there is nothing lik H3O compound !! so the concentration of this ion determines the 'strength' of an acid .. also an acid solution is acidic due to this ion ..
i'll tell u something .. DRY HCl gas doesnt turn blue litmus red .. y ?? because u need to WET the litmus to gain the change the colour diff .. when u wet it H+ ions are produced with are acidic ;)
-
hmmm
isnt this supposed to be MG0 + H2?
MARK SCHEME SAYS A :/
Which year is it??? I mean if it isn't an official document from CIE, (like the ones for 00 or 01 here) it has mistakes....
-
Plus one final thing people, in June 2000, shouldn't question 30 be C??? (Paper 1 Chemistry)
Can someone please help me here too?? The mark scheme says that if you add S02 to water, the pH goes above 7 (alkaline)
-
A student carries out an experiment to prepare pure magnesium sulfate crystals.
The diagram shows the first stage of the preparation.
In diagram :
-dilute sulfuric acid
-stirrer
-magnesium carbonate
He adds magnesium carbonate until no more reacts.
Which process should he use for the next stage?
A crystallisation
B evaporation
C filtration
D neutralisation
I thght it's A. But turns out it's C. Is Magnesium sulphate insoluble in water? :S
-
oct / nov 1997
anwa a tricky question ( for me anyway ) i got it wrong ..asnwr is A
asner should be filtration..you filter first then evaporate
-
oct / nov 1997
anwa a tricky question ( for me anyway ) i got it wrong ..asnwr is A
asner should be filtration..you filter first then evaporate
A - CH4 + 2O2 = CO2 + 2H2O
H2O = colorless liquid......
CO2 = colorless gas - limewater milky
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Can someone please help me here too?? The mark scheme says that if you add S02 to water, the pH goes above 7 (alkaline)
i cant open that paper??!!
-
A student carries out an experiment to prepare pure magnesium sulfate crystals.
The diagram shows the first stage of the preparation.
In diagram :
-dilute sulfuric acid
-stirrer
-magnesium carbonate
He adds magnesium carbonate until no more reacts.
Which process should he use for the next stage?
A crystallisation
B evaporation
C filtration
D neutralisation
I thght it's A. But turns out it's C. Is Magnesium sulphate insoluble in water? :S
No. All sulphates except those lead, barium and calcium are soluble.
You filter to remove any excess magnesium carbonate (which is insoluble). Adding it till no more reacts means that you must've added some excess magnesium carbonate (which is insoluble). First it must be removed by filtration then crystallisation can be used to obtain magnesium sulphate crystals
-
oct / nov 1997
anwa a tricky question ( for me anyway ) i got it wrong ..asnwr is A
asner should be filtration..you filter first then evaporate
easy .. look at the options .. try CH4 first .. does it burn in air to give water and CO2 ?? yes .. voila !! water is 100 *C boiling pt and CO2 lime watre colourless to cloudy..
answer is A
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No. All sulphates except those lead, barium and calcium are soluble.
You filter to remove any excess magnesium carbonate (which is insoluble). Adding it till no more reacts means that you must've added some excess magnesium carbonate (which is insoluble). First it must be removed by filtration then crystallisation can be used to obtain magnesium sulphate crystals
Oh God that was so obvious!!! LOL...THANKSSSSSSSSSSS! :)
-
CAN SOMEONE PLEASE TELL ME WHAT IS PRECIPITATION???
Also... when the give u an equation.. how do u know if it is a redox or oxidation???
Please Notify me :)
-
i cant open that paper??!!
Sorry for the delay.....
-
Sorry for the delay.....
is the ans C ??
-
CAN SOMEONE PLEASE TELL ME WHAT IS PRECIPITATION???
Also... when the give u an equation.. how do u know if it is a redox or oxidation???
Please Notify me :)
Precepitation is when a solid forms when two liquids are mixed together (for example neutralisation reactrions)
-
Thanks ...
now can someone tell me.. how do u know if an equation is given if the reaction is redox or oxidizing??
-
Sorry for the delay.....
Clearly the ms is rong if it says ph>7.
-
Thanks ...
now can someone tell me.. how do u know if an equation is given if the reaction is redox or oxidizing??
check the previous pages for a sample solved question on exactly the same thing
-
is the ans C ??
shouldnt it be A?
-
shouldnt it be A?
above 7 would be basic .. the other option says blue to red .. shows for acidic
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ALRIGHTY THEN !
GOOD LUCK GUYS 2MRW
ILL LEAVE YOU TONGIHT WITH MR. AADII AND MR. VIN TO ASNWER YOUR QUESTIONS !!! I WISH ALL OF YOU THE BEST OF LUCK !! AND IF U WANNA LIGHTEN UP GO VISIT THE JOKES AND RIDDLES POSTS ( LORD KRATOS <3)
GOOD LUCK AGAIN
AND THANKS VIN AND AADI
GOOOOOOOOOD NIIIIIIIGHHHHHHHHHTTTTTTTTTTTTTTT SF!
-
ALRIGHTY THEN !
GOOD LUCK GUYS 2MRW
ILL LEAVE YOU TONGIHT WITH MR. AADII AND MR. VIN TO ASNWER YOUR QUESTIONS !!! I WISH ALL OF YOU THE BEST OF LUCK !! AND IF U WANNA LIGHTEN UP GO VISIT THE JOKES AND RIDDLES POSTS ( LORD KRATOS <3)
GOOD LUCK AGAIN
AND THANKS VIN AND AADI
GOOOOOOOOOD NIIIIIIIGHHHHHHHHHTTTTTTTTTTTTTTT SF!
gd night kimo :D ..Talk to you later ;)
-
Someone please explain. I don't get! Especially why last one isnt redox. Thanks
-
S + 02 --> S02
S - oxidation number 0..
O2 - oxidation number 0
SO2 --> oxidation number of O = (-2*2) = -4 , thus oxidation number of S = +4
S--> 0 to 4 oxidation
O -> 0 to -4 reduction
thus redox.
2S02 + 02-->2 S03
2SO2 -> oxidation number of O = (-2*2) = -4, thus S = +4. O2 -> 0, final of O = -4+0 = -4
SO3--> Oxidation number of O = (-2*3) = -6, of S = +6
Final , S --> 4 to 6 oxidation
O --> -4 to -6 reduction
SO3 + H20--> H2SO4
SO3 --> O = (-3*2) = -6 , thus S = +6
H2O --> O = -2, thus H = +2
O in both compounds thus, final number of O = -6-2 = -8
H2SO4--> O = (-2*4) = -8, thus H = +2, as final oxidation number of the compound shud be 0, -8+2+S = 0
thus, S = +6
now the changes
S --> 6 to 6
H --> 2 to 2
O --> -8 to -8..
NOt redox.
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this drove me crazy during my IGCSEs too..
S + 02 --> S02
S - oxidation number 0..
O2 - oxidation number 0
SO2 --> oxidation number of O = (-2*2) = -4 , thus oxidation number of S = +4
S--> 0 to 4 oxidation
O -> 0 to -4 reduction
thus redox.
2S02 + 02-->2 S03
2SO2 -> oxidation number of O = (-2*2) = -4, thus S = +4. O2 -> 0, final of O = -4+0 = -4
SO3--> Oxidation number of O = (-2*3) = -6, of S = +6
Final , S --> 4 to 6 oxidation
O --> -4 to -6 reduction
SO3 + H20--> H2SO4
SO3 --> O = (-3*2) = -6 , thus S = +6
H2O --> O = -2, thus H = +2
O in both compounds thus, final number of O = -6-2 = -8
H2SO4--> O = (-2*4) = -8, thus H = +2, as final oxidation number of the compound shud be 0, -8+2+S = 0
thus, S = +6
now the changes
S --> 6 to 6
H --> 2 to 2
O --> -8 to -8..
NOt redox.
In the first one, why are the oxidation state of S and of 02 zero? :S
Thanks. :)
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The equation shows the reaction between a halogen and the aqueous ions of another halogen.
X2 + 2Y- ? 2X- + Y2
What could X2 and the colour of Y– be?
A chlorine, brown
B chlorine, colourless
C iodine, brown
D iodine, colourless
Answer is B..... ??? ??? ??? :-\ HOWWWWWWWWWWWWWW? Plzz help me out someone!
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In the first one, why are the oxidation state of S and of 02 zero? :S
Thanks. :)
Oxidation States of Elements is always 0. Its a rule.
"The oxidation number of any free element is zero."
here : http://www.chemistry.wustl.edu/~courses/genchem/Labs/RedoxIdentity/oxidation.htm
3rd one
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Oxidation States of Elements is always 0. Its a rule.
Thanks a million! :D
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The equation shows the reaction between a halogen and the aqueous ions of another halogen.
X2 + 2Y- ? 2X- + Y2
What could X2 and the colour of Y– be?
A chlorine, brown
B chlorine, colourless
C iodine, brown
D iodine, colourless
Answer is B..... ??? ??? ??? :-\ HOWWWWWWWWWWWWWW? Plzz help me out someone!
has to be chlorine, as it is more reactive than iodine. halide ions are always colourless ;D
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plz explain Q20 year november 2007
thx in advance
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Thanks a million! :D
no problem, check the post again..check the link :D
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S + 02 --> S02
S - oxidation number 0..
O2 - oxidation number 0
SO2 --> oxidation number of O = (-2*2) = -4 , thus oxidation number of S = +4
S--> 0 to 4 oxidation
O -> 0 to -4 reduction
thus redox.
2S02 + 02-->2 S03
2SO2 -> oxidation number of O = (-2*2) = -4, thus S = +4. O2 -> 0, final of O = -4+0 = -4
SO3--> Oxidation number of O = (-2*3) = -6, of S = +6
Final , S --> 4 to 6 oxidation
O --> -4 to -6 reduction
SO3 + H20--> H2SO4
SO3 --> O = (-3*2) = -6 , thus S = +6
H2O --> O = -2, thus H = +2
O in both compounds thus, final number of O = -6-2 = -8
H2SO4--> O = (-2*4) = -8, thus H = +2, as final oxidation number of the compound shud be 0, -8+2+S = 0
thus, S = +6
now the changes
S --> 6 to 6
H --> 2 to 2
O --> -8 to -8..
NOt redox.
why is oxidation number 4 in first one, sone pls explain
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plz explain Q20 year november 2007
thx in advance
carbon reacts with air to form carbon dioxide, released, so mass of carbon decreases.
copper reacts wtih oxygen to form copper oxide, which is soluble, so gets accumulated.
so answer is b
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has to be chlorine, as it is more reactive than iodine. halide ions are always colourless ;D
O_O....I think I need another pair of glasses XD...
Thanks a lot. Really nice of all of you to help out like this! :)
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eee the OVERALL oxidation state of a COMPOUND is 0. that doesnt mean the elements IN the compound also have 0 as the oxidation number...
for SO2...
Oxygen has a fixed oxidation number, but not sulfur, so first we determine the oxidation number of O2 = (-2*2+ = -4
now as i told previously, the OVERALL oxidation state of a COMPOUND has to be 0
so S has to be +4 to make the overall oxidation no. of SO2 = 0
this way -4+4 = 0
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plz explain Q20 year november 2007 AND Q38 plz
thx in advance
??? ??? ??? :-\ :-\ :-\ :-[
i'm waitin ::) ::)
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is the ans C ??
Yes it should be C!!!! THat's what I thought too! But that no good unofficial mark scheme claims its A (which is impossible!!! I'll chop my hands if someone proves its A).
Plus one final thing, why should aqueous copper sulphate be used in electroplating something with copper. Why not only a molten copper salt. And in M/J 2007 question 16 what is the answer??? PLZ HELP!!!
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Sorry don't answer mj 07. I didn't see that it had been answered
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Yes it should be C!!!! THat's what I thought too! But that no good unofficial mark scheme claims its A (which is impossible!!! I'll chop my hands if someone proves its A).
Plus one final thing, why should aqueous copper sulphate be used in electroplating something with copper. Why not only a molten copper salt. And in M/J 2007 question 16 what is the answer??? PLZ HELP!!!
u talking about refining copper?
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eee the OVERALL oxidation state of a COMPOUND is 0. that doesnt mean the elements IN the compound also have 0 as the oxidation number...
for SO2...
Oxygen has a fixed oxidation number, but not sulfur, so first we determine the oxidation number of O2 = (-2*2+ = -4
now as i told previously, the OVERALL oxidation state of a COMPOUND has to be 0
so S has to be +4 to make the overall oxidation no. of SO2 = 0
this way -4+4 = 0
So all compunds have oxidation number of 0?
Then why is it that sulphur is +4, i thought cos it's in group 6, then it is -2.
how do oxidation numbers work?
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u talking about refining copper?
NO! electroplating something (a key) with copper....
-
??? ??? ??? :-\ :-\ :-\ :-[
i'm waitin ::) ::)
Has been answered previously
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Has been answered previously
where , give me the link ,or number of page plz ???
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Both the options can be used, however, having molten CuSO4 uses more energy and thus its wiser to use aqueous copper sulfate.
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Q)
What is a Basic oxide?
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plz explain Q20 year november 2007
thx in advance
answer is B .. because carbon will react with oxygen from air to form CO2 and escape .. so mass of carbon dec.
copper reacts with O2 to form oxide which 'gains' mass due to oxygen
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where , give me the link ,or number of page plz ???
carbon reacts with air to form carbon dioxide, released, so mass of carbon decreases.
copper reacts wtih oxygen to form copper oxide, which is soluble, so gets accumulated.
so answer is b
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So all compunds have oxidation number of 0?
Then why is it that sulphur is +4, i thought cos it's in group 6, then it is -2.
how do oxidation numbers work?
its not possible to explain everything now...its a long long concept..
check the website i had posted earlier and read the rules..that shud help u
@helium = a metal oxide that is base, which forms a hydroxide when ombined with water.
i didnt say all compounds have oxidation number of 0, the OVERALL! oxidation number is 0...like SO2, if O2's is -4, then S's shud be +4 to make the overall oxidation number 0.
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Q)
What is a Basic oxide?
metal oxide
-
its not possible to explain everything now...its a long long concept..
check the website i had posted earlier and read the rules..that shud help u
@helium = a metal oxide that is base, which forms a hydroxide when ombined with water.
i didnt say all compounds have oxidation number of 0, the OVERALL! oxidation number is 0...like SO2, if O2's is -4, then S's shud be +4 to make the overall oxidation number 0.
sory which website?
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carbon reacts with air to form carbon dioxide, released, so mass of carbon decreases.
copper reacts wtih oxygen to form copper oxide, which is soluble, so gets accumulated.
so answer is b
what abt Q35 :-[ :-[
-
Q)
What is a Basic oxide?
*ahem* google .. :P
reacts with acid to give salt and water
reacts with water to give a base
-
carbon reacts with air to form carbon dioxide, released, so mass of carbon decreases.
copper reacts wtih oxygen to form copper oxide, which is soluble, so gets accumulated.
so answer is b
35) A , K + Na = 1 + 6.5 = 7.5
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sory which website?
http://www.chemistry.wustl.edu/~courses/genchem/Labs/RedoxIdentity/oxidation.htm
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*ahem* google .. :P
reacts with acid to give salt and water
reacts with water to give a base
Thanks thats what i wanted
-
??? ??? ??? :-\ :-\ :-\ :-[
i'm waitin ::) ::)
38) B - it burns in air, it dissolves.. it cannot be polymerized.
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what abt Q35 :-[ :-[
ok the only elements "singly" charged are Na and K add 6.5 and 1 = 7.5 ie A
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umm y Na and K particularly , y not Ca or Mg
read the q, it says "Single charged" i.e +1
Ca 2+ and Mg2+, no single charged
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read the q, it says "Single charged" i.e +1
Ca 2+ and Mg2+, no single charged
i posted this and then i removed it cuz i knew i wasn daydreamin or smthn
thx ...............man i owe u :o lol ::)
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i posted this and then i removed it cuz i knew i wasn daydreamin or smthn
thx ...............man i owe u :o lol ::)
exactly i clicked the link it took me to the top of the page .. i thought somethings wrong with my browser .. :P
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i posted this and then i removed it cuz i knew i wasn daydreamin or smthn
thx ...............man i owe u :o lol ::)
LOL, nah its k, or probably, as stewie griffin might say "Oh most certainly woman, Time will tell. VICTORY IS MINE!"
:P
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exactly i clicked the link it took me to the top of the page .. i thought somethings wrong with my browser .. :P
hehe
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can somebody help me with this question???i dont understand anything about it... ??? ???
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LOL, nah its k, or probably, as stewie griffin might say "Oh most certainly woman, Time will tell. VICTORY IS MINE!"
:P
haha .. LOL :D
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can somebody help me with this question???i dont understand anything about it... ??? ???
ok liquid Y is water .. tht u got ?? when water is added to anhydrous CuSO4 the colour changes from white to blue and ALWAYS its an exothermic reaction .. so C .. i guess
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can somebody help me with this question???i dont understand anything about it... ??? ???
Hydrated copper sulfate --> Anhydrous copper sulfate + water
Anhydrous copper sulfate is white..when water is added , it turns blue.
Adding water to anhydrous copper(II) sulfate is exothermic. thus heat given out.
Answer :C
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ok liquid Y is water .. tht u got ?? when water is added to anhydrous CuSO4 the colour changes from white to blue and ALWAYS its an exothermic reaction .. so C .. i guess
SO they were just askin what happens in the reverse reaction
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Hydrated copper sulfate --> Anhydrous copper sulfate + water
Anhydrous copper sulfate is white..when water is added , it turns blue.
Adding water to anhydrous copper(II) sulfate is exothermic. thus heat given out.
Answer :C
thanks V1N and adi
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SO they were just askin what happens in the reverse reaction
yup .. the question says tht .. when Y is added to X
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Aadi .. always one step ahead :) .. hey can u tell me how can i been more confidant about my answers ?? like this one for instance ..
when i am confidant the answers go wrong .. :\
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Guys is there a specific volume for which a pipette can be used? I mean a range of volumes???
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Guys is there a specific volume for which a pipette can be used? I mean a range of volumes???
typical ones in a lab 10, 25, and 50 ml. (at least in my school lab) y do you ask ??
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Aadi .. always one step ahead :) .. hey can u tell me how can i been more confidant about my answers ?? like this one for instance ..
when i am confidant the answers go wrong .. :\
The only way you can be confident about your answers if you have all your concepts in the right place. Try to read that IGCSE chem. guide b4 sleeping, thats nuff. YOu dont need tips dude, ur awesome, and im sure ull get that star in chem ;)
@deadman - Typical volumes are 10, 25, and 50 mL. Alternatively, graduated pipettes are straight-walled, and graduated for different volumes such as 5 mL in 0.5 mL increments.
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The only way you can be confident about your answers if you have all your concepts in the right place. Try to read that IGCSE chem. guide b4 sleeping, thats nuff. YOu dont need tips dude, ur awesome, and im sure ull get that star in chem ;)
@deadman - Typical volumes are 10, 25, and 50 mL. Alternatively, graduated pipettes are straight-walled, and graduated for different volumes such as 5 mL in 0.5 mL increments.
i read what u wrote ::) ::) and i'm just wondering can u give me the link ::)
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i read what u wrote ::) ::) and i'm just wondering can u give me the link ::)
what link?
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what link?
to the IGCSE chem guide thingy
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to the IGCSE chem guide thingy
its a book
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Thanks Aadi .. r u talking about this guide ?? I still hav to do French .. havnt touched it since morning !
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its a book
Oh tht ! tht is more than enough .. sad i dont hav the whole book. :\ jus a couple of pages photocopies ..
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typical ones in a lab 10, 25, and 50 ml. (at least in my school lab) y do you ask ??
Thanks a lot. No nothing really. Just random stuff :P.
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Thanks a lot. No nothing really. Just random stuff :P.
oh ok .. there is something known as teat pipette .. or dropper .. which is smaller and less accurate than a pipette ;) you obvi. might know this ..:)
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Some body prove it's A.(plz)
It's unsaturated because it has a double bond, but why form neutral solution
in water. It has OH group which is alcohols.
-
Thanks Aadi .. r u talking about this guide ?? I still hav to do French .. havnt touched it since morning !
hey vin dude do u have de guide
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oh ok .. there is something known as teat pipette .. or dropper .. which is smaller and less accurate than a pipette ;) you obvi. might know this ..:)
hahaha I do know this. It's the stuff we use to mess around with the lab's chemicals when the teacher is busy ;D..
Just one final thing (really sorry to disturb today), in oct/nov 01 in question 13, why is it not A (P only)???
-
Some body prove it's A.(plz)
It's unsaturated because it has a double bond, but why form neutral solution
in water. It has OH group which is alcohols.
O/N 2003 CHEM P1 , Q36!
Which compound is unsaturated and forms a neutral solution in water?
A) CH2OH-CH--CH-CH2OH
B) CH2OH-CH2-CH2-CH2OH
C) CO2H-CH--CH-CO2H
D) CO2H-CH2-CH2-CO2H
i get the unsaturated bit.. but how do you know if it's neutral or not?
doesnt the 'OH' group make it ... acidic? :B hehs, explanation neeeeeded svp, (X
:P
answer is A .. why because C doesnt make sense to me ! also OH is alcohol and COOH is acid
looooool - uhh but howd you know that alcohols can form neutral solutions in water? :(
It is supposed to be neutral .. in fact red litmus paper has an ingredient called "alcohol" .. thts a long story now .. google it if u wanna
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hahaha I do know this. It's the stuff we use to mess around with the lab's chemicals when the teacher is busy ;D..
Just one final thing (really sorry to disturb today), in oct/nov 01 in question 13, why is it not A (P only)???
lol same here, our students act like 9 year old, take the syringes and start spraying water at
each other.
Are u sure the anw is A.
Q)which Group 7 element is produced at which anode.
1 solution has Molten lead(II) bromide. Bromine gas produced at P.
2 solution concentrated hydrochloric acid. Chlorine is supposed to be formed at R.
I think it should be B (P and R)
Or chloride ions dont move in concentrated solutions
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hey vin dude do u have de guide
http://thenightdreamer.wordpress.com/2009/11/11/chemistry-guide/
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Thanks Vin,
Looks like it's a long story ;D
-
hahaha I do know this. It's the stuff we use to mess around with the lab's chemicals when the teacher is busy ;D..
Just one final thing (really sorry to disturb today), in oct/nov 01 in question 13, why is it not A (P only)???
canu post the paper plz? and abt the unsaturated thingy
Its A or C. It cant be C because C is an acid and it wudnt be neutral. Alchol in water will be neutral
-
lol same here, our students act like 9 year old, take the syringes and start spraying water at
each other.
Are u sure the anw is A.
Q)which Group 7 element is produced at which anode.
1 solution has Molten lead(II) bromide. Bromine gas produced at P.
2 solution concentrated hydrochloric acid. Chlorine is supposed to be formed at R.
I think it should be B (P and R)
Or chloride ions dont move in concentrated solutions
i think he asked why is is not A
can u post the options too ?? i dont seem to get the paper ,, u made my life easy tho by posting the ques .. u are right .. its both ;)
-
Thanks Vin,
Looks like it's a long story ;D
LOL .. someone had asked me earlier i thought i'd post everything .. so tht u dont hav the same doubts :P
-
canu post the paper plz? and abt the unsaturated thingy
Its A or C. It cant be C because C is an acid and it wudnt be neutral. Alchol in water will be neutral
yup if u r talking about
Some body prove it's A.(plz)
It's unsaturated because it has a double bond, but why form neutral solution
in water. It has OH group which is alcohols.
-
lol same here, our students act like 9 year old, take the syringes and start spraying water at
each other.
Are u sure the anw is A.
Q)which Group 7 element is produced at which anode.
1 solution has Molten lead(II) bromide. Bromine gas produced at P.
2 solution concentrated hydrochloric acid. Chlorine is supposed to be formed at R.
I think it should be B (P and R)
Or chloride ions dont move in concentrated solutions
Yeah it is B ohhh sh*t!!! I forgot chlorine is an element of group 7! AHHHHHHHHHH. I mean everything is correct then suddenly I do something very stupid. Don't ever get 40. Either it's 39 or 38.. I hate myself......
-
Okay, good luck everyone, do well. :D
-
Yeah it is B ohhh sh*t!!! I forgot chlorine is an element of group 7! AHHHHHHHHHH. I mean everything is correct then suddenly I do something very stupid. Don't ever get 40. Either it's 39 or 38.. I hate myself......
i know ..same happens to me .. i messed up one question in my mock .. we got the winter 09 paper .. same ditto with no changes .. i lost one mark there .. wish i would hav solved tht paper before .. would hav got full !! ;D
-
WHAT IS SOLOUBLE AND INSOLUBLE SALT
CAN ANY 1 TELL ME
PLAESE ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ???
-
can someone explain this fast in may june 2009 chemistry paper 1 q 6 it says the electronic configuration of an ion is 2,8,8 wat could this ion be it gave me a table with right and wrong for S 2- CA 2+ and choose both why??????
-
WHAT IS SOLOUBLE AND INSOLUBLE SALT
CAN ANY 1 TELL ME
PLAESE ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ???
soluble salt is FULLY miscible in water .. and leaves no precipitation in the tube ..
insoluble salt DOES NOT 'mix' with water or not soluble and leaves some precipitate behind
-
WHAT IS SOLOUBLE AND INSOLUBLE SALT
CAN ANY 1 TELL ME
PLAESE ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ???
-All Chlorides, bromides and iodides are soluble except lead chloride/bromide/iodide, silver Cl/Br/I, and mercury Cl/Br/I
-All sulphates are soluble except lead sulphate, barium sulphate and calcium sulphate
-All carbonates are insoluble except Sodium, potassium (All group 1 metals in general) and ammonium carbonates, which are soluble.
-All hydroxides are insoluble except Sodium, potassium(All group 1 metals in general), ammonium, calcium, strontium and barium hydroxides, which are soluble.
-All nitrates are soluble
heres the list
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i know ..same happens to me .. i messed up one question in my mock .. we got the winter 09 paper .. same ditto with no changes .. i lost one mark there .. wish i would hav solved tht paper before .. would hav got full !! ;D
That happens at your place too??? HAHAHAHA lol. Our teacher tried to be extra clever so he mixed nov 09 gce with igcse nov 09. HAHAH but we had already LEARNED all the answers in both of em' :D. 90% of the class got 40 :D.
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can someone explain this fast in may june 2009 chemistry paper 1 q 6 it says the electronic configuration of an ion is 2,8,8 wat could this ion be it gave me a table with right and wrong for S 2- CA 2+ and choose both why??????
Sulfur - 16
2,8,6 if it gainst 2 electrons, 2,8,8
Calcium - 20
2,8,8,2 if it loses 2 electrons , 2,8,8
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can someone explain this fast in may june 2009 chemistry paper 1 q 6 it says the electronic configuration of an ion is 2,8,8 wat could this ion be it gave me a table with right and wrong for S 2- CA 2+ and choose both why??????
ok the electronic config. of
Ca = 2,8,8,2
S =2,8,6
so when Ca loses both e- and S gains 2 e- they form 2,8,8 or ions
Ca has the valency of +2
S has the valency of -2
so, A
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That happens at your place too??? HAHAHAHA lol. Our teacher tried to be extra clever so he mixed nov 09 gce with igcse nov 09. HAHAH but we had already LEARNED all the answers in both of em' :D. 90% of the class got 40 :D.
LOL not only for paper 1 but for all chem papers .. so our sir kept the boundary as 95% for A* in mock :P but most of us got abv 90%
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LOL not only for paper 1 but for all chem papers .. so our sir kept the boundary as 95% for A* in mock :P but most of us got abv 90%
Man for us it was nov 09 (all papers) in Physics and Chemistry!!!! LOL Bio was MOSTLY gce nov 09. Maths and English weren't from past papers..
In our school, 90% for A* is fixed so our teacher then decided to cut marks for odd things lol :D.
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oooh thanks 1 more plz in question 8 same exam it says element v forms an acidic covalent oxide which row in the table shows how many electrons there could be in the outer shell of an atom of v (1 2 6 7 ) in ms they choose 6 and 7 why
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oooh thanks 1 more plz in question 8 same exam it says element v forms an acidic covalent oxide which row in the table shows how many electrons there could be in the outer shell of an atom of v (1 2 6 7 ) in ms they choose 6 and 7 why
ok listen .. always ..
acidic oxide is a non-metal ..
also covalent means involving a non-metal ..
ALL non-metals have a valency starting from 4, 5, 6, 7 .. because they need to gain electrons .. u may find this in the "Periodic Table" chapter in your book .. if it has .. consider revising it .. ;) got it ??
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-All Chlorides, bromides and iodides are soluble except lead chloride/bromide/iodide, silver Cl/Br/I, and mercury Cl/Br/I
-All sulphates are soluble except lead sulphate, barium sulphate and calcium sulphate
-All carbonates are insoluble except Sodium, potassium (All group 1 metals in general) and ammonium carbonates, which are soluble.
-All hydroxides are insoluble except Sodium, potassium(All group 1 metals in general), ammonium, calcium, strontium and barium hydroxides, which are soluble.
-All nitrates are soluble
heres the list
MINE! :P (c) !
-
thanks mate u r the best :D
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hahahahahahha Shaz be generous!!! So you're finally online! (I was wondering where you were)!!!
-
YAAAAAAAAA!!!!!!!!!!!!!!!!!!!!! I'm not a newbie any more!!! (By the way how did that change?? It's not like I'm helping a lot of people. Infact I'm troubling them :D.)
-
can u plz explain y this thank u any1
:)
-
http://thenightdreamer.wordpress.com/2009/11/11/chemistry-guide/
THANKZ VINY:P
-
can u plz explain y this thank u any1
:)
The answer is C.
This is because, the air in the jar contains, along with all the other components in the air, OXYGEN. This OXYGEN, i.e 21% is USED UP by the iron fillings as they react with it to form iron oxide, i.e rust, which is also hydrated.
As the oxygen is used up, water in the tube rises to replace the lost volume of the oxygen.
-
Can someone explain Q4, 22 of w08 paper 1, thanks
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YAAAAAAAAA!!!!!!!!!!!!!!!!!!!!! I'm not a newbie any more!!! (By the way how did that change?? It's not like I'm helping a lot of people. Infact I'm troubling them :D.)
number of posts .. ;)
-
The answer is C.
This is because, the air in the jar contains, along with all the other components in the air, OXYGEN. This OXYGEN, i.e 21% is USED UP by the iron fillings as they react with it to form iron oxide, i.e rust, which is also hydrated.
As the oxygen is used up, water in the tube rises to replace the lost volume of the oxygen.
hey shazii can u plz tell de equation of rusting
-
explain plz i m sry i m realli dumb
-
explain plz i m sry i m realli dumb
ethanol..................draw them and u'll kno what i'm talkin abt
By the way no one is dumb ;)
-
can u plz explain y this thank u any1
:)
there is no equation as such .. Fe2O3.xH2O because the water content is not the same in all cases
Rusting requires
CO2
H2O
O2
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there is no equation as such .. Fe2O3.xH2O because the water content is not the same in all cases
Rusting requires
CO2
H2O
O2
c02? why would u need that?
-
Can someone explain Q4, 22 of w08 paper, thanks
For Q4, recall that IONIC COMPOUNDS are SOLUBLE in water while COVALENT COMPOUNDS are NOT.
In the first method, X, i.e the ionic salt, will dissolve in the water, as is soluble, leaving Y behind.
Y, as a solid residue, may be obtained via filtering, where X is in solution.
In method 2, Usually both DO NOT dissolve in ethanol.
So only method one is workable, thus the answer is B.
In Q22,
experiment 1 is a simple test for the presence of ammonium ion. recall that sodium hydroxide is added to an ammonium containing compound. Alkaline ammonia gas will produce on heating, turning the red paper blue, and the other blue will remain blue.
In experiment 2, a soluble salt CANNOT react with an acid, so no reaction, thus no change in colour of litmus paper.
Thus ans is D.
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explain plz i m sry i m realli dumb
C, because has formula: C2H5OH
-
explain plz i m sry i m realli dumb
H H
| |
H - C - C - O - H
| |
H H
ETHANOL C2H5OH
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Yo noobs go to sleep we are failing anyways xD ;D ;D
Lol m gonna stay for another half an hour :P Anyone wants to ask :)?
-
Yo noobs go to sleep we are failing anyways xD ;D ;D
Lol m gonna stay for another half an hour :P Anyone wants to ask :)?
nah actually i'm going to bed
Talk to you later people of this universe ::)
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For Q4, recall that IONIC COMPOUNDS are SOLUBLE in water while COVALENT COMPOUNDS are NOT.
In the first method, X, i.e the ionic salt, will dissolve in the water, as is soluble, leaving Y behind.
Y, as a solid residue, may be obtained via filtering, where X is in solution.
In method 2, Usually both DO NOT dissolve in ethanol.
So only method one is workable, thus the answer is B.
In Q22,
experiment 1 is a simple test for the presence of ammonium ion. recall that sodium hydroxide is added to an ammonium containing compound. Alkaline ammonia gas will produce on heating, turning the red paper blue, and the other blue will remain blue.
In experiment 2, a soluble salt CANNOT react with an acid, so no reaction, thus no change in colour of litmus paper.
Thus ans is D.
Ok, I get 22. BUt for 4, why in MS it says A? So apparantly ionic salts are not soluble in ethanol butr organic covalent are?
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Ok, I get 22. BUt for 4, why in MS it says A? So apparantly ionic salts are not soluble in ethanol butr organic covalent are?
yes
-
ethanol..................draw them and u'll kno what i'm talkin abt
By the way no one is dumb ;)
but dat dumb ms is sayin its ethene i noe i m nt dumb :P was makin sure of de answer
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Ok, I get 22. BUt for 4, why in MS it says A? So apparantly ionic salts are not soluble in ethanol butr organic covalent are?
So, apparently, COVALENT ORGANIC COMPOUNDS are SOLUBLE in ETHANOL! :S
-
So, apparently, COVALENT ORGANIC COMPOUNDS are SOLUBLE in ETHANOL! :S
Can anyone explain why ionic are insoluble and organic covalent are soluble in ethanol?
-
Can anyone explain why ionic are insoluble and organic covalent are soluble in ethanol?
Somestuff my son, can't be explained -.- >.< Seriously, why do u want to confuse ur self? I don't think anyone here knows why cuz its so detailed... U dont need to know ;)
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Can anyone explain why ionic are insoluble and organic covalent are soluble in ethanol?
Yar Shaz guide parh guide!!!!
@ VIN why is CO2 needed for rusting???? Heard it for the first time in my life ....
-
Vin, like my new signature xD ;D ;D ;D??
-
Yar Shaz guide parh guide!!!!
@ VIN why is CO2 needed for rusting???? Heard it for the first time in my life ....
I think he meant iron, not co2. Its definetly iron, o2, h2o
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Yar Shaz guide parh guide!!!!
@ VIN why is CO2 needed for rusting???? Heard it for the first time in my life ....
i think cuz CO2 is a acidic oxide which react with iron oxide 2 form Fe2O3.XH2O n yet dere used also water be present
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i think cuz CO2 is a acidic oxide which react with iron oxide 2 form Fe2O3.XH2O n yet dere used also water be present
bullshit ;D xD
what is said is true... written in my book...
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i think cuz CO2 is a acidic oxide which react with iron oxide 2 form Fe2O3.XH2O n yet dere used also water be present
Not possible. It will make it Fe2O3C.xH20 something. It will cause rust to contain carbon...
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Let's make it straight solubility will depend on the ionic strength of solutions. You need to learn what is polarity(which we dont have) umm example "Like compounds dissolve Like compound"
ethanol is an organic compound .. ions dont disassociate in ethanol
ionic compounds can only disassociate into water
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Somestuff my son, can't be explained -.- >.< Seriously, why do u want to confuse ur self? I don't think anyone here knows why cuz its so detailed... U dont need to know ;)
LOL .. perfect explanation .. XD
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Yar Shaz guide parh guide!!!!
@ VIN why is CO2 needed for rusting???? Heard it for the first time in my life ....
I dont know why the f** i sai it .. sorry .. ;\ .. its like im studying french n chemi bot side by side .. ;D
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Baladya please don't mind it but I really want to ask this. Your name has got me inching with curiosity. Do you know Arabic?? Baladaya as that municipal department??? :D :D :D.
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LOL .. perfect explanation .. XD
;D Would get me an A* xD Thats enough :P ;D
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Baladya please don't mind it but I really want to ask this. Your name has got me inching with curiosity. Do you know Arabic?? Baladaya as that municipal department??? :D :D :D.
People asked me this like a million time :D
And yes as if in mechnical warever but thats not how i got it :P It's the name of a club in Egypt but people think its cuz i like baladya (rubbish and stuff)
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Vin, like my new signature xD ;D ;D ;D??
dude .. i love your sig. holds very true for some people :P not on SF tho .. talking abt real life .. ;D
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dude .. i love your sig. holds very true for some people :P not on SF tho .. talking abt real life .. ;D
I wish it was like: YOU wish your parents had used it :P
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hey vinny is gettin rough thanx 2 municipality but still dunt understand do ve use CO2 in rusting n ya one more can u explain this question below realli dont get it
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neutralisation reaction is with acid and base right? can it be with hydrocloric acid and sodium carbonate and why when it is carbonate not base
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hey vinny is gettin rough thanx 2 municipality but still dunt understand do ve use CO2 in rusting n ya one more can u explain this question below realli dont get it
B, right?
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hey vinny is gettin rough thanx 2 municipality but still dunt understand do ve use CO2 in rusting n ya one more can u explain this question below realli dont get it
NO!! he said it was a mistake.. CO2 isnt used in rusting. Only o2 and water and iron. Thats rusting
As for ur question, notice that the four are bonded to each other, so its P4. If it was 2 bonded to each other and another two bonded then its 2P2. the number before shows the number of molecules while the number after shows how many atoms stuck together
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B, right?
Ya as i explained
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hey vinny is gettin rough thanx 2 municipality but still dunt understand do ve use CO2 in rusting n ya one more can u explain this question below realli dont get it
I dont know why the f** i sai it .. sorry .. ;\ .. its like im studying french n chemi bot side by side .. ;D
Listen to Baladya as he says .. ;) u;ll get an A*
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neutralisation reaction is with acid and base right? can it be with hydrocloric acid and sodium carbonate and why when it is carbonate not base
No.!! Only Acid + Base. Other Acid reactions like Carbonates do produce salts but they are not neutralisation reactions...
Right Vin?
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NO!! he said it was a mistake.. CO2 isnt used in rusting. Only o2 and water and iron. Thats rusting
As for ur question, notice that the four are bonded to each other, so its P4. If it was 2 bonded to each other and another two bonded then its 2P2. the number before shows the number of molecules while the number after shows how many atoms stuck together
hey but in de ms is written P4 NOT 4P
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hey but in de ms is written P4 NOT 4P
thats what i said...
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hey vinny is gettin rough thanx 2 municipality but still dunt understand do ve use CO2 in rusting n ya one more can u explain this question below realli dont get it
Answer is P4 shows a molecule of Phosphorous
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cuz i found it and ms says it is neutralisation
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cuz i found it and ms says it is neutralisation
dunno :S maybe m wrong, check with VIN ;)
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neutralisation reaction is with acid and base right? can it be with hydrocloric acid and sodium carbonate and why when it is carbonate not base
It is a neutralisation reaction..
Acid + Carbonate ------> Salt + Water + Carbon dioxide
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OK guys im signing off .. its almost 4am here !! .. BEST OF LUCK !! DO WELL :D
-
Hey when we add excess zinc to acid (to make salt)
Why is it excess? I understand but i dunno what to write... should i write to have a complete reaction, or to obtain as much salt as posibble?
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OK guys im signing off .. its almost 4am here !! .. BEST OF LUCK !! DO WELL :D
GL noob :D Sleep well ;)
-
vin where r u living man omg its 4 am
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Hey when we add excess zinc to acid (to make salt)
Why is it excess? I understand but i dunno what to write... should i write to have a complete reaction, or to obtain as much salt as posibble?
To ensure all acid is used up (yes produce maximum yield of salt).
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OK guys im signing off .. its almost 4am here !! .. BEST OF LUCK !! DO WELL :D
VIN, have you got Chem tomorrow?
-
To ensure all acid is used up (yes produce maximum yield of salt).
thx :D
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vin where r u living man omg its 4 am
lol wtf what are u doing so late xD
here its 1:30 AM
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Hey when we add excess zinc to acid (to make salt)
Why is it excess? I understand but i dunno what to write... should i write to have a complete reaction, or to obtain as much salt as posibble?
yea so that all the acid is reacted to form salt, then filter ..if asked
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lol wtf what are u doing so late xD
here its 1:30 AM
umm .. solving doubt !?! :P
studying french .. ;)
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vin where r u living man omg its 4 am
china .. lol jk .. INDIA .. southern Asia
(http://www.blythemcgarvie.com/images/IndianGlobe_200w.jpg)
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yea so that all the acid is reacted to form salt, then filter ..if asked
Anyway i m sure this will not come... been coming in exams a lot now xD
By the way Vin, warever ur religion is, be sure that god will reward u for ur help to everyone here ;)
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VIN, have you got Chem tomorrow?
yup .. how do u think im able to answer these chem ques .. :P not perfectly correct tho but i manage to answer some ;D
-
Anyway i m sure this will not come... been coming in exams a lot now xD
By the way Vin, warever ur religion is, be sure that god will reward u for ur help to everyone here ;)
Thank you .. i need your blessings .. ;) and of the almighty GOD!!
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lol wtf what are u doing so late xD
here its 1:30 AM
huh go die over here its 2:34 AM :P
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phenolphthalein
srry for the spam but i think this will help me remember the name xD ;D The guy who inveted the name is sick xD
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ya u r helpful VIN.... ;)
do have some sleep!.....surely...lol...thou i sleep so less nowadays.... :P
its 2:30 here!!.. ;)..im gona sleep in an hour or so....XD
GOOD LUCK EVERYONE!!!... :D :D :D
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china .. lol jk .. INDIA .. southern Asia
(http://www.blythemcgarvie.com/images/IndianGlobe_200w.jpg)
hw jobless can u turn u actualli showed me ON DE MAP lolz :o :o ;D ;D ;D hey gud luck 4 chem n ya thanz 4 de helps :P:)
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Best thing they did is the exam at 3:30.. I can wake late, and actually revise more :P but its hot tho :S
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heyy nidzz.....where do u live??..we have the same tym!!.. :P
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heyy nidzz.....where do u live??..we have the same tym!!.. :P
i noe UAE where is u
-
me UAE too.... :D
yayyy!!...hi5!!
lol..we hav morning paper .....which skool?
-
hey ppl how do u obtain lime from limestone?
can anyone just give a quick explanation tht wud be really helpful!!....and wat reaction is it endo or exothermic?
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hey ppl how do u obtain lime from limestone?
can anyone just give a quick explanation tht wud be really helpful!!....and wat reaction is it endo or exothermic?
CaCO3 ----> CaO + CO2
It is heated at high temperature. It is endothermic as energy is needed...
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hey ppl how do u obtain lime from limestone?
can anyone just give a quick explanation tht wud be really helpful!!....and wat reaction is it endo or exothermic?
CaCO3 ----> CaO + CO2
thermal decomposition (endo)
CaO + H2O --> Ca(OH)2
exo
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hw jobless can u turn u actualli showed me ON DE MAP lolz :o :o ;D ;D ;D hey gud luck 4 chem n ya thanz 4 de helps :P:)
it takes 2 secs .. thanks to google ;)
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VIN go to sleep man >.<
k m off boobs :D GN ;)
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kk..ya Thanks baladya..... ;)
and u did all pasrpapers?..and wat else did u do today for chem??..imean revised any special chapters..or anything do temme....Thanks...=D
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kk..ya Thanks baladya..... ;)
and u did all pasrpapers?..and wat else did u do today for chem??..imean revised any special chapters..or anything do temme....Thanks...=D
I revised Chem from book very fast today. Only have 3 lessons i will do tommorow, and when i finish that, i will go over some questions i had doubt with b4 in past papers and i marked them :P
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VIN go to sleep man >.<
k m off boobs :D GN ;)
yea u r there to handle so i dont need to worry ;)
LOL XD ..
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ok cool!!....... :D..bst ov luck for exam!!
and ya ppl .....anyone..... u guys suggest any year tht was hard for chem p1.......plz temme so i can revise again!!
Thanks all..=D
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me UAE too.... :D
yayyy!!...hi5!!
lol..we hav morning paper .....which skool?
westminister ahhh i thnk i noe u MAYBE u 4rm egypt rght ahh blahh
@vin stil wasted @MIN n noe i order u 2 go sleep man y torturin urself n noe it wuld be 5 dere rgth
i shuld be nt de de one sayin this i m awake de whole nght :P
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no not frm egypt...:P
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can any1 explain this HAMZ u dere
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can any1 explain this HAMZ u dere
noble gas is the last group
it always have 8 electrons in the last shell, therefore answer is B
bcause it has 8 electrons, it's stable and is unreactive
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oh sorry nidzz i was away!!
ya someone's right...its last shell has 8 electrons ..it has a structure like neon!!
-
... help pleaseeee
-
... help pleaseeee
Wht is the ans?
-
Wht is the ans?
D.....
-
... help pleaseeee
Hang on
-
Hang on
okayyy, :/
-
See the number (VII) thats written after the word dichromate ?? Thats the OXIDATION state.
If that number changes then the oxidation state changes too.
BUT in this case it hasnt so the OXIDATION STATE IS THE SAME.
SO the answer is C or D
Next EXCESS K(OH) was added so the pH for an alkali is 12ish. So the pH would INCREASE
ANSWER is D
Which year is this from ?
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See the number (VII) thats written after the word dichromate ?? Thats the OXIDATION state.
If that number changes then the oxidation state changes too.
BUT in this case it hasnt so the OXIDATION STATE IS THE SAME.
SO the answer is C or D
Next EXCESS K(OH) was added so the pH for an alkali is 12ish. So the pH would INCREASE
ANSWER is D
Which year is this from ?
OHOHHHHHOH, thankss ;D
uhmm, M/J 08 :)
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hard one
answer is A ?why
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2 more...
! Q11 & Q39
for q39, answer's D, but i thought carboxylic acids & alcohols have the same number of H? since its CnH2n+1OH and CnH2n+1COOH
:S helpppppp pleasee !!!!! :( :( :( :(
exams in an hourrrrr, hahahahahaha..
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2 more...
! Q11 & Q39
for q39, answer's D, but i thought carboxylic acids & alcohols have the same number of H? since its CnH2n+1OH and CnH2n+1COOH
:S helpppppp pleasee !!!!! :( :( :( :(
exams in an hourrrrr, hahahahahaha..
u said the asnwer is D
thats an ETHENE AND CARBOXYLIC ACID
it works ^
andwer for 11 is D also
...you have to do the ocmubstion reaction and balance
-
why is answer A
isnt smaller give it a larger S.A?
-
u said the asnwer is D
thats an ETHENE AND CARBOXYLIC ACID
it works ^
andwer for 11 is D also
...you have to do the ocmubstion reaction and balance
.. ohhhh, then why doesnt it work for ethanoic acid and ethanol??? both has 6 Hydrogen atoms aswell/? :( :( :( no?
and for Q11, it's B.
-
why is answer A
isnt smaller give it a larger S.A?
Your correct; the answer you gave is from a teacher's mark scheme remember that.
-
Your correct; the answer you gave is from a teacher's mark scheme remember that.
alright can u check the firsst post on this page??
and this 1 tooo
whyy?
not B ..lead is also a trans metal
-
asnwer is D???
is it caz CO + O2 is exothermic?
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why C not A??
i pretended that Mn is a trans metla like silver and lead and so i thought A?
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I'm confused, in electrolysis when we say that there's a H2O ion, a substance is concentrated or when it is aqueous?
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I'm confused, in electrolysis when we say that a substance is concentrated or when it is aqueous that we have to keep in mind there's a H2O ion?
nop not when its concentrated !!!!
ex CONC NA CL
H+ AND CL- WILL FORM !!
and Na will form as a metal deposit!
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i got my questions answered guys ! from a freind not in sf
thanks ! ( no need to anser them now )
-
^^So when it's concentrated we say it has H2O?
And another question M/J 2009 Q26.
What does the fact that it's green has to do with anything?
-
pls help me wit this.the answer is B.why?
why the pH does not change when we add NaCl??
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pls help me wit this.the answer is B.why?
why the pH does not change when we add NaCl??
NACL IS A SALT...( NETURAL )
NOT ALKALINE OR ACIDIC.
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^^So when it's concentrated we say it has H2O?
And another question M/J 2009 Q26.
What does the fact that it's green has to do with anything?
I DUNNO I HAEVA DIFF VARIANT
By the way if i were id go study electrolysis again caz u haev the whole concept wrong and electrolysis is very common !
CONC . has ntothign to do with water
dilute And aqueos haev somehtin to do with water
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Exactly, I actually studied it pretty well and then I read all those posts about concentrated and stuff and they've been pretty confusing since I know that Aq means it is dissolved in water.
Anyways Oct/Nov 2008 Q3, Why is it Aqueous lead (II) nitrate and not dilute sulfuric acid?
And also M/J 2009 Q26.
What does the fact that it's green has to do with anything?
-
NACL IS A SALT...( NETURAL )
NOT ALKALINE OR ACIDIC.
ooohh...okay,thanks :D
-
srry ,, an emergency question .
why is zinc hydroxide added to sulfuric acid in solid form ?
-
srry ,, an emergency question .
why is zinc hydroxide added to sulfuric acid in solid form ?
I dont think ZnOH is available in solid for ?!? ???
-
hard one
answer is A ?why
Im kinda confused too .. :-\
Take this for eg ..
Mg + H2O ---> MgO + H2 .. single displaced reaction .. "convert molecules to a new substance by removing Hydrogen atoms" ..
also, FeS + HCl ---> FeCl2 + H2S .. double displacement reaction .."convert molecules to a new substance by removing Hydrogen atoms"
-
Morning guyz, wen do ur exams start??
-
alright can u check the firsst post on this page??
and this 1 tooo
whyy?
not B ..lead is also a trans metal
but PbBr2 is SUPPOSED to be white
-
Morning guyz, wen do ur exams start??
Chem p1 and French p2 .. DONE ;)
-
alright can u check the firsst post on this page??
and this 1 tooo
whyy?
not B ..lead is also a trans metal
wats the answer? A??
-
Chem p1 and French p2 .. DONE ;)
exam done?? so y are u guyz discussing it?
-
asnwer is D???
is it caz CO + O2 is exothermic?
yes it is used as a fuel in the industries .. nitrogen on its own is not combustible
-
exam done?? so y are u guyz discussing it?
umm .. only for me :P
-
Exactly, I actually studied it pretty well and then I read all those posts about concentrated and stuff and they've been pretty confusing since I know that Aq means it is dissolved in water.
Anyways Oct/Nov 2008 Q3, Why is it Aqueous lead (II) nitrate and not dilute sulfuric acid?
And also M/J 2009 Q26.
What does the fact that it's green has to do with anything?
3)Lead Nitrate + Ba2+ + I- = Lead iodide + Barium nitrate. (soluble, thus will dissociate back into ions)
Lead iodide insoluble, yellow ppt. Barium nitrate, soluble.
with H2SO4, barium sulfate, insoluble, wont dissociate to ions, thus no Ba2+ ions...
Green - Iron salt
thus iron - high melting poinbt high density
-
how did chem p1 go ppl?? bio p31 WUZ hard n LOOONG.....WAAYY too mch wrtin n ecology....
-
Oct/Nov 2008 Q3, Why is it Aqueous lead (II) nitrate and not dilute sulfuric acid?
And also M/J 2009 Q26.
What does the fact that it's green has to do with anything?
Oct/Nov 2008 Q15, Why is it A (Decrease of 20) I did the calculations and I got 5?
Can anyone please help on those questions??
-
how did chem p1 go ppl?? bio p31 WUZ hard n LOOONG.....WAAYY too mch wrtin n ecology....
We are not allowed to say anything about the paper ;)
-
Oct/Nov 2008 Q3, Why is it Aqueous lead (II) nitrate and not dilute sulfuric acid?
And also M/J 2009 Q26.
What does the fact that it's green has to do with anything?
Oct/Nov 2008 Q15, Why is it A (Decrease of 20) I did the calculations and I got 5?
Can anyone please help on those questions??
3)Lead Nitrate + Ba2+ + I- = Lead iodide + Barium nitrate. (soluble, thus will dissociate back into ions)
Lead iodide insoluble, yellow ppt. Barium nitrate, soluble.
with H2SO4, barium sulfate, insoluble, wont dissociate to ions, thus no Ba2+ ions...
26)Green - Iron salt
thus iron - high melting poinbt high density
15) Endothermic, so heat taken in. Decrease of 20 degrees. 5grams in 500cm^3 will take in more heat. U might have used direct proportion in ur calculations, its inversely proportional here...
-
Oct/Nov 2008 Q3, Why is it Aqueous lead (II) nitrate and not dilute sulfuric acid?
And also M/J 2009 Q26.
What does the fact that it's green has to do with anything?
Oct/Nov 2008 Q15, Why is it A (Decrease of 20) I did the calculations and I got 5?
Can anyone please help on those questions??
Oct/Nov 2008 Q3
aqueous lead(II) nitrate combines with barium iodide to form lead iodide which is insoluble and yellow in colour .. leaving behind Ba2+ ions
M/J 2009 Q26.
A - because the "transition metals" form coloured salt compounds
which hav a high meting pt and high density
-
We are not allowed to say anything about the paper ;)
i didnt ask nythn ....i meant hard or eazi..... :)
-
A@di, sorry, I still don't understand Oct/Nov 2008 Q15 but thanks for the other explanations.
By the way, can list down all the important metals/transition metals/non-metals with their colours and their salts' colours?
And if Barium nitrate (or any other soluble substance) is soluble, it means we can break it down into it's ions? Therefore, we can say that Barium is formed? And the insoluble substance is what gives off the precipitate?
-
A@di, sorry, I still don't understand Oct/Nov 2008 Q15 but thanks for the other explanations.
By the way, can list down all the important metals/transition metals/non-metals with their colours and their salts' colours?
And if Barium nitrate (or any other soluble substance) is soluble, it means we can break it down into it's ions? Therefore, we can say that Barium is formed?
It dissociates in water, Barium is not formed, BARIUM IONS are formed. Yes insoluble salts are precipitates ..
about Q15) Same mass dissolving in less volume, more heat will be taken in. Inversely proportional, (10*1000)/500 = 20'C
Nickel salts - Green
Iron(II) salts - Green
Copper salts - Blue
Calcium salts - red
-
Right, Thanks so much, I understand it all now!!
-
Right, Thanks so much, I understand it all now!!
Ur welcome. good luck for the paper.
-
Right, Thanks so much, I understand it all now!!
go kill the paper my friend :D :D ;)
-
can some1 give me the mark scheme
of m/j and oct/ nov 2001
-
Chem Paper 1 - awesome! Piece of cake. :P I love. lol
-
Chem Paper 1 - awesome! Piece of cake. :P I love. lol
variant 1 or 2??
-
Xainalley : Variant 2 :D
-
^^OMG I want that!!
My exams is 3 hours away, I'm using every second of it to study.
Anyways, I know I've been a heavy load but another question,
Oct/Nov 2008 Q20.
Thanks again, and sorry for the constant trouble...
-
hi guys
anybody finish chemistry paper 1 ??? ??? ??? ??? ??? ???
-
paper was easy :DD
P.L.S DO NOT ASK ME WHAT IS IN IT
-
ok
where do u live?
takamorinki
-
Anybody has the reactivity series list? If so, post them and thanks.
-
Anyways, I know I've been a heavy load but another question,
Oct/Nov 2008 Q20 and Q21 (why is it Sulfuric acid and not HCL?)
Thanks again, and sorry for the constant trouble...
-
Anybody has the reactivity series list? If so, post them and thanks.
http://www.ellen-wilkinson-school.co.uk/Departments/Science/tests/Metals/reactivity.gif
-
Done with Chem P1. :) Easy.
-
Anybody has the reactivity series list? If so, post them and thanks.
-
Anybody has the reactivity series list? If so, post them and thanks.
Potassium (Please)
Sodium (Send)
Calcium (Cows)
Magnesium (Monkeys)
Aluminium (And)
Carbon
Zinc (Zebras)
Iron (In)
Lead (Large)
Hydrogen
Cuppor (Cages)
;D ;D ;D ;D ;D
-
Anyways, I know I've been a heavy load but another question,
Oct/Nov 2008 Q20 and Q21 (why is it Sulfuric acid and not HCL?)
Thanks again, and sorry for the constant trouble...
20) Barium chloride and Nitric acid. pH decreases, ppt. doesnt form as Barium chloride is soluble.
21) Sulfuric acid, Barium sulfate formed , white ppt. HCl wud produce barium chloride which is soluble.
-
ok
where do u live?
takamorinki
in the middle east
-
Potassium (Please)
Sodium (Send)
Calcium (Cows)
Magnesium (Monkeys)
Aluminium (And)
Carbon
Zinc (Zebras)
Iron (In)
Lead (Large)
Hydrogen
Cuppor (Cages)
;D ;D ;D ;D ;D
LOL at your signature! XD
-
heheeheheh xD ;D I WISH my parents used it :D
-
heheeheheh xD ;D I WISH my parents used it :D
ROFLOL! :D
-
20) Barium chloride and Nitric acid. pH decreases, ppt. doesnt form as Barium chloride is soluble.
21) Sulfuric acid, Barium sulfate formed , white ppt. HCl wud produce barium chloride which is soluble.
So the PH decreases because chloride is an alkline therefore it neutralises it?
Plus is it always that when an acid reacts with an oxide it forms a salt?
-
So the PH decreases because chloride is an alkline therefore it neutralises it?
pH decreases because nitric acid is formed.. ph<7 = acidic..
Barium nitrate + HCl = Barium nitrate + Nitric acid.
-
heheeheheh xD ;D I WISH my parents used it :D
LOLLLLLLLLLLLLLLLLLLLLLLLLLL...can't stop laughin!!! I wish my examiner's parents had used it ;)
-
^^Barium chloride + HCl= Barium nitrate + Nitric acid.?
Typo?
But is Chlorine and Chlorides overall acidic or basic?
and is it always that when an acid reacts with an oxide it forms a salt?
-
^^Barium chloride + HCl= Barium nitrate + Nitric acid.?
Typo?
But is Chlorine and Chlorides overall acidic or basic?
and is it always that when an acid reacts with an oxide it forms a salt?
sorry, typo.
acidic or basic depends on OH- and H+ ions being present not chlorides/chlorine.
no not always..reactivity series
-
anyone tell me what the test of water related to cobalt chloride..
when is it pink and when is it beomes blue ?? ???
-
A new isotope of a divalent metal is discovered. Some students are asked to predict its
properties.
Which student’s predictions are correct?
number of electrons - bonding in the oxide
in outer shell
A 2 covalent
B 2 ionic
C 6 covalent
D 6 ionic
Why is it B and not D?
-
A new isotope of a divalent metal is discovered. Some students are asked to predict its
properties.
Which student’s predictions are correct?
number of electrons - bonding in the oxide
in outer shell
A 2 covalent
B 2 ionic
C 6 covalent
D 6 ionic
Why is it B and not D?
I think its because they said "metal"
-
A new isotope of a divalent metal is discovered. Some students are asked to predict its
properties.
Which student’s predictions are correct?
number of electrons - bonding in the oxide
in outer shell
A 2 covalent
B 2 ionic
C 6 covalent
D 6 ionic
Why is it B and not D?
Firstly because it is a METAL so its valency must be 2, and cannot be 6, because it would be a non-metal then.
Secondly because, it's a METAL OXIDE, which is ionic, i.e metal and non metal.
-
anyone tell me what the test of water related to cobalt chloride..
when is it pink and when is it beomes blue ?? ???
When water is added to cobalt chloride, cobalt chloride turns from blue to pink
-
A new isotope of a divalent metal is discovered. Some students are asked to predict its
properties.
Which student’s predictions are correct?
number of electrons - bonding in the oxide
in outer shell
A 2 covalent
B 2 ionic
C 6 covalent
D 6 ionic
Why is it B and not D?
First you need to understand the term valency and valence electrons.
Valency is the no of electrons required to lose/gain/share in order to achieve a stable electronic configuration.
Valence electrons are the no of electrons in the outermost shell of the atom.
Divalent= 2 valence electrons
So B
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hello...can sumone help me?
im sure this is a very easy question and that everyone can answer except for me!
how does the proton number influence the periodic table? ???
please help!thanksss! ;D
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hello...can sumone help me?
im sure this is a very easy question and that everyone can answer except for me!
how does the proton number influence the periodic table? ???
please help!thanksss! ;D
Very easy, proton number determines the element. If you look at 1 particular period on the periodic table, then you'll see when proton number increases by 1, the element is the next group in the same period. Got it? :D
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Very easy, proton number determines the element. If you look at 1 particular period on the periodic table, then you'll see when proton number increases by 1, the element is the next group in the same period. Got it? :D
got it!thanks! ;D
and do u happen to know any example for intimate mixing?
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if you lose 15 marks in bio paper 3, is it still possible to get an A*
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if you lose 15 marks in bio paper 3, is it still possible to get an A*
What about paper 1 and 6?
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What about paper 1 and 6?
i get 32/40in paper 6 and 38/40 in paper 1 and 65-70/80 in paper 3
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i get 32/40in paper 6 and 38/40 in paper 1 and 65-70/80 in paper 3
It all depends on your Paper 3 performance.
I wish you the best - study hard and concentrate. Pray for me too. ;)
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I HAVE A DOUBT THAT I CANNOT JUST GET!!
the question gave the height of precipitates with different volumes of one of the soluble salts dat were reacted 2 give da ppt nd we have to find the formula of the other soluble salt.
SO HOW DO WE FIND IT???
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Here is one example ...
It came as a graph in paper3 may/june 2009 Q5
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Here is another question, can u explain how we can we get da formula for both questions, plz?
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Have no idea how to do it :-\,
but doin research to find out cause i also need to know.
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Here is one example ...
It came as a graph in paper3 may/june 2009 Q5
this was answered somewhere before. I'll look for the explanation
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guys what is the big idea about MOLES , Like i study the chapter from my textbook , but when i open the
past papers i cant really solve anything .. ?
the moles are partially hard
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nope they're the easiest part of chemistry ;)
Just post your question here...I'll answer 'em :) I have AS chem tom :P
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pls,
can somebody answer for me q5 in 2002 june....
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2002%20Jun/0620_s02_qp_3.pdf
no answer on ms...i just wanna check my answers...
thx
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the a) part?
Liquids take the shape of the container, they maintain their volume. The intermolecular forces in liquids are significant and therefore, they do not expand to occupy all the space available (as gases do). A given mass of liquid has a fixed volume. also molecules in liquid have less k.e as compared to that of gases.Particles in gases have very weak intermolecular forces and high kinetic energy, hence the particles move independent of each other and occupy the space available to them.
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the a) part?
Liquids take the shape of the container, they maintain their volume. The intermolecular forces in liquids are significant and therefore, they do not expand to occupy all the space available (as gases do). A given mass of liquid has a fixed volume. also molecules in liquid have less k.e as compared to that of gases.Particles in gases have very weak intermolecular forces and high kinetic energy, hence the particles move independent of each other and occupy the space available to them.
thanks 8)...pls try to solve for me the questions on the last page pls....if u have time ;)
thx
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b)i) rate= time and volume. In other words, its the volume produced and the time taken.
ii) CO2 due to lower molecular mass. or less density
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b)i) rate= time and volume. In other words, its the volume produced and the time taken.
ii) CO2 due to lower molecular mass. or less density
thx... :D
and the last page please....i really su*k in mole calculations :'(...if possible,with some explanations pls.... :)
thx
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thx... :D
and the last page please....i really su*k in mole calculations :'(...if possible,with some explanations pls.... :)
thx
The equation you need to use is:
Volume of gas (in dm3)
Moles of gas = --------------------------
24
Note to convert cm3 to dm3, divide quantity by 1000 (e.g. 20cm3/1000=0.02dm3)
This is the proper theory and equation behind my calculations below.
Here are the answers for 5) c) as requested:
i) Moles of C4H6: 0.02/24=0.000833
From equation, we know 2 moles of C4H6 reacts with 11 moles of O2
Therefore, moles of O2: 0.000833*5.5=0.00458
Therefore, volume of O2: 4.58*24*1000=110cm3
ii) From equation, we know 2 moles of C4H6 produces 8 moles of CO2
Therefore, moles of CO2: 0.000833*4=0.00333
Therefore, volume of CO2: 0.00333*24*1000=80cm3
iii) From equation, we know 2 moles of C4H6 produces 6 moles of H2O
Therefore, moles of H2O: 0.000833*3=0.0025
Therefore, volume of H2O: 0.0025*24*1000=60
Therefore, total volume of gases is simply volume of CO2 + volume of H2O:
80+60=140cm3
Alternatively, 8+6=14, so 2 moles of C4H6 produces 14 moles of products
Therefore, moles of products: 0.000833*7=0.00583
Therefore, volume of products: 0.00583*24*1000=140cm3
For part d), you use this formula:
Mass
Moles = ------
Mr
d) From the above equation, 1 mole of butyne forms 3 moles of water
Number of moles of butyne reacted: 9/54=0.167
Number of moles of water formed: 0.167*3=0.5
Mass of water formed: 0.5*(2+16)=9g
I hope this has helped. :D
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@Ivo +rep :) Keep it up !
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The equation you need to use is:
Volume of gas (in dm3)
Moles of gas = --------------------------
24
Note to convert cm3 to dm3, divide quantity by 1000 (e.g. 20cm3/1000=0.02dm3)
This is the proper theory and equation behind my calculations below.
Here are the answers for 5) c) as requested:
i) Moles of C4H6: 0.02/24=0.000833
From equation, we know 2 moles of C4H6 reacts with 11 moles of O2
Therefore, moles of O2: 0.000833*5.5=0.00458
Therefore, volume of O2: 4.58*24*1000=110cm3
ii) From equation, we know 2 moles of C4H6 produces 8 moles of CO2
Therefore, moles of CO2: 0.000833*4=0.00333
Therefore, volume of CO2: 0.00333*24*1000=80cm3
iii) From equation, we know 2 moles of C4H6 produces 6 moles of H2O
Therefore, moles of H2O: 0.000833*3=0.0025
Therefore, volume of H2O: 0.0025*24*1000=60
Therefore, total volume of gases is simply volume of CO2 + volume of H2O:
80+60=140cm3
Alternatively, 8+6=14, so 2 moles of C4H6 produces 14 moles of products
Therefore, moles of products: 0.000833*7=0.00583
Therefore, volume of products: 0.00583*24*1000=140cm3
For part d), you use this formula:
Mass
Moles = ------
Mr
d) From the above equation, 1 mole of butyne forms 3 moles of water
Number of moles of butyne reacted: 9/54=0.167
Number of moles of water formed: 0.167*3=0.5
Mass of water formed: 0.5*(2+16)=9g
I hope this has helped. :D
thanks man ;D....bath rocks!!! ;)
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Whats heated and instead of melting turns into solid? ???
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huh...when you heat anything, molecules in it will always move away from each other.
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Whats heated and instead of melting turns into solid? ???
I don't get what you mean by "whats heated", and for your second question, freezing/solidification is the process of turning a liquid into a solid.
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naah, it's just one of my friends planning to take chem next year,
so he challenged me to anwser that question, he said it's eggs, LOL :D
Yes i know it sounds lame , i told him a chemical reaction took place when boiling or cooking the egg,
but he still loves that question ;D
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*yawn* ::)
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hy can some1 gime the list of soluble and insluble cmpounds..?
its differnt in diffrent books..
wht doeeeeeeeees CIE approve of?
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All nitrates are soluble.
All ammonium, sodium, potassium, lithium compunds are soluble.
With sulphates, all are soluble excep for barium, leade, and calcium.
With halides, all are soluble except for lead and silver
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Whats heated and instead of melting turns into solid? ???
I suppose you're referring to sublimation. Carbon Dioxide. When solid carbon dioxide is heated (it's called dry ice By the way) it turns into a gas instead of becoming a liquid...
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All nitrates are soluble.
All ammonium, sodium, potassium, lithium compunds are soluble.
With sulphates, all are soluble excep for barium, leade, and calcium.
With halides, all are soluble except for lead and silver
Also most hydroxides and carbonates are insoluble except Group I hydroxides and carbonates (calcium hydroxide is slightly soluble).
Most metal oxides are insoluble except Group I and II oxides react with water.
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yo ivo!
just 1 question,on the answer that u gave me,the last answer...y did u do o.5*(2+16)??
where did 2 and 16 came from?
sorry if this is a silly question because I'm very bad in chem.... :'(
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and please if somebody can do this... ???
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also, guys, don't know why my computer's decided to be all retarded today, but i'm not able to download the "questions paper 1 from 1994-2004" on this link: http://freeexampapers.com/Dndex.php?d=SUdDU0UvQmlvbG9neS9DSUUvMTk5MyAtIDIwMDM=
or the answers to it (first file)
it's for biology, and my computer keeps saying that it's a reported malicious site or something.
please help?????!!!!!
this is strange its workin for me......the message u get is frm ur browser of frm ur antvitus software
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this is strange its workin for me......the message u get is frm ur browser of frm ur antvitus software
i think freeexampapers.com got hacked or attacked by virus....
my browser keeps telling me that this site is attacked....
but i still can download the papers....though being prompted by my browser every time i click.....
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i think freeexampapers.com got hacked or attacked by virus....
my browser keeps telling me that this site is attacked....
but i still can download the papers....though being prompted by my browser every time i click.....
-
its working for me comletely no messages no probs..
-
i think freeexampapers.com got hacked or attacked by virus....
my browser keeps telling me that this site is attacked....
but i still can download the papers....though being prompted by my browser every time i click.....
Why would anyone try to hack freeexampapers?
it's working with me
-
download it from www.xtremepapers.net
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hey guys,
M/J 2002 Paper 1 for biology isn't posted on FEP... the mark scheme is, but the actual paper isn't.. does anyone know where I can find it?
thanksss :)
Here it is aangel42, please find the attached file. Hope that's what you want :D
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yo ivo!
just 1 question,on the answer that u gave me,the last answer...y did u do o.5*(2+16)??
where did 2 and 16 came from?
sorry if this is a silly question because I'm very bad in chem.... :'(
Looking at that previous post, and applying the formula, you notice I used the term 'Mr'. This just simply means the relative molecular mass - the sum of the relative atomic masses in the formula of the molecule.
The formula of water is: H2O, so looking at the periodic table: (Ar of O: 16; Ar of H: 1). This means: H2=1+1, and O is just 16. So in total, the Mr is: 16+2=18.
Sorry for not explaining this in the first place. I hope this helps :)
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also, guys, don't know why my computer's decided to be all retarded today, but i'm not able to download the "questions paper 1 from 1994-2004" on this link: http://freeexampapers.com/Dndex.php?d=SUdDU0UvQmlvbG9neS9DSUUvMTk5MyAtIDIwMDM=
or the answers to it (first file)
it's for biology, and my computer keeps saying that it's a reported malicious site or something.
please help?????!!!!!
OK, see if you can download them by clicking on these links. If not, let me know.
Questions Paper 1 June 1994 -- 2004.pdf:
http://www.freeexampapers.us/IGCSE/Biology/CIE/1993%20-%202003/Questions%20Paper%201%20June%201994%20--%202004.pdf (http://www.freeexampapers.us/IGCSE/Biology/CIE/1993%20-%202003/Questions%20Paper%201%20June%201994%20--%202004.pdf)
Answers June 1993 -- 2003 P1, 3, & 6.pdf:
http://www.freeexampapers.us/IGCSE/Biology/CIE/1993%20-%202003/Answers%20June%201993%20--%202003%20P1,%203,%20&%206.pdf (http://www.freeexampapers.us/IGCSE/Biology/CIE/1993%20-%202003/Answers%20June%201993%20--%202003%20P1,%203,%20&%206.pdf)
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and please if somebody can do this... ???
OK, hopefully this clears your doubt.
This time, you'll need to also apply this formula:
Concentration (mol/dm3) = Moles / Volume (dm3)
So:
i) Number of moles of NaOH used = 2.24*0.025 = 0.056 mols
ii) Maximum number of moles of Na2SO4.10H2O that could be formed = From the equation given, you can see 2 moles of NaOH gives 1 mole of Na2SO4.10H2O. So it is simply: 0.056/2 = 0.028 mols
iii) Mass of one mole of Na2SO4.10H2O = 322g
iv) Maximum yield of sodium sulphate-10-water = 0.028*322 = 9.02g
v) Percentage yield = (3.86/9.02)*100 = 42.8%
If you don't understand any of this, I'll be happy to explain ;)
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OK, hopefully this clears your doubt.
This time, you'll need to also apply this formula:
Concentration (mol/dm3) = Moles / Volume (dm3)
So:
i) Number of moles of NaOH used = 2.24*0.025 = 0.056 mols
ii) Maximum number of moles of Na2SO4.10H2O that could be formed = From the equation given, you can see 2 moles of NaOH gives 1 mole of Na2SO4.10H2O. So it is simply: 0.056/2 = 0.028 mols
iii) Mass of one mole of Na2SO4.10H2O = 322g
iv) Maximum yield of sodium sulphate-10-water = 0.028*322 = 9.02g
v) Percentage yield = (3.86/9.02)*100 = 42.8%
If you don't understand any of this, I'll be happy to explain ;)
double thanks man ;D...
+rep twice on u.... ;)
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Okay guys you will kill me for this but i don't seem to get it .. I don't know why! :-\
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Okay guys you will kill me for this but i don't seem to get it .. I don't know why! :-\
It's hard to give a concrete explanation, but we know it's between pH and temperature. I would go for pH as I've seen in many textbooks that the effect of pH on the activity is more of a natural parabola than for temperature. I suppose, when increasing temperature above the optimum temperature, the activity suddenly decreases more than if pH increased, I guess.
Sorry for giving you a slightly blurred explanation, but that's the best I can do, hope that helps a little :). Consider the effect of temperature and pH below, and make your judgement ;) This is a very good graph as the effects of the two variables are given side by side.
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Ok thanks .. I get it ;) :D
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Hiiii, um there doesnt seem to be any answers to Q5 onwards in the MS for M/J 02.
http://freeexampapers.com/FreeExamPapers.com_.php?__lo=SUdDU0UvQ2hlbWlzdHJ5L0NJRS8yMDAyIEp1bi8wNjIwX3MwMl9tc18zLnBkZg==
i've tried xtreme papers as well..
:-\ help?
thaaanks
-
Look at the examiner's report ;)
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Look at the examiner's report ;)
THANK YOU! ;D
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can somebody answer these questions and please tell me y?? :-\
thanks
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anybody knows some good website/sources to learn about moles in chemistry? or just chemistry in basic? I really messed up in physics I dont want the same to happen in chemistry.. :'(. Help greatly appreciated
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http://www.s-cool.co.uk/gcse/chemistry.html
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I've got a huuuuuuge doubt.
If Mole = Mass / RFM , and here, they're asking for the number of moles of sodium atoms reacted.
So to find the mole of 2Na .. isn't it 11.5/46 = 0.25 Mole? :-\
And if it's only 11.5/23 , which equals to 0.5, isn't that only ONE atom of Na but we need two here so dont we multiply the answer by 2? D:
Help please.. ???
Thaaanks!
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I've got a huuuuuuge doubt.
If Mole = Mass / RFM , and here, they're asking for the number of moles of sodium atoms reacted.
So to find the mole of 2Na .. isn't it 11.5/46 = 0.25 Mole? :-\
And if it's only 11.5/23 , which equals to 0.5, isn't that only ONE atom of Na but we need two here so dont we multiply the answer by 2? D:
Help please.. ???
Thaaanks!
But Moles of Na exist as mono atomic .. so each mole of Na has one atom of Na not 2.. so if you say you have 1 mole of Na , its the same as 1Mole of atoms of Na..Why did you divide by 46?
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Just follow the equation:
2Na + S --------> Na2S
46 32
11.5 10(but excess so we wont use this)
We know that 11.5g of Na reacted .. so just use the simple formula .. mass/RFM .. 11.5/23 = 0.5moles
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Just follow the equation:
2Na + S --------> Na2S
46 32
11.5 10(but excess so we wont use this)
We know that 11.5g of Na reacted .. so just use the simple formula .. mass/RFM .. 11.5/23 = 0.5moles
um um um.. wait so even if its 2Na .. it's still gonna be 0.5moles? ???
isn't 0.5 for 1Na? :-\
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um um um.. wait so even if its 2Na .. it's still gonna be 0.5moles? ???
isn't 0.5 for 1Na? :-\
You ignore the equation.. You have 11.5g of Na in your hands .. and they react .. so how many moles that were in your hands reacted?
11.5/23 .. Dont let the balancing of the equation mix you up..
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You ignore the equation.. You have 11.5g of Na in your hands .. and they react .. so how many moles that were in your hands reacted?
11.5/23 .. Dont let the balancing of the equation mix you up..
OHHHHHHHH. so the 2Na's just to tell you that if you need to find the mole for the reacted Sulphur, you divide 0.5/2 ..?
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can somebody answer these questions and please tell me y?? :-\
thanks
The answer to your first question is B, because it asks for passage of water, so water is always lost by transpiration (water vapour diffuses out of plant through stoma).
Second question is A, general rule, both atria contract at the same time, both ventricles contract at the same time. The only given option for this rule is A, because there is no option for Z and Y.
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can somebody answer these questions and please tell me y?? :-\
thanks
mmm...anybody please explain to me the questions on my previous post.... :'( :'(
it's on the previous page...
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mmm...anybody please explain to me the questions on my previous post.... :'( :'(
it's on the previous page...
I've answered it, please check the mark scheme and tell me if I am right.
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The answer to your first question is B, because it asks for passage of water, so water is always lost by transpiration (water vapour diffuses out of plant through stoma).
Second question is A, general rule, both atria contract at the same time, both ventricles contract at the same time. The only given option for this rule is A, because there is no option for Z and Y.
ooohh....sorry man....didnt see it... :-[
yeah,ur right...
thx for the explanation :D
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Hiiii, um there doesnt seem to be any answers to Q5 onwards in the MS for M/J 02.
http://freeexampapers.com/FreeExamPapers.com_.php?__lo=SUdDU0UvQ2hlbWlzdHJ5L0NJRS8yMDAyIEp1bi8wNjIwX3MwMl9tc18zLnBkZg==
i've tried xtreme papers as well..
:-\ help?
thaaanks
All of Q5 has been answered previously, I hope this is good enough, obviously not the mark scheme though! :D
the a) part?
Liquids take the shape of the container, they maintain their volume. The intermolecular forces in liquids are significant and therefore, they do not expand to occupy all the space available (as gases do). A given mass of liquid has a fixed volume. also molecules in liquid have less k.e as compared to that of gases.Particles in gases have very weak intermolecular forces and high kinetic energy, hence the particles move independent of each other and occupy the space available to them.
b)i) rate= time and volume. In other words, its the volume produced and the time taken.
ii) CO2 due to lower molecular mass. or less density
The equation you need to use is:
Volume of gas (in dm3)
Moles of gas = --------------------------
24
Note to convert cm3 to dm3, divide quantity by 1000 (e.g. 20cm3/1000=0.02dm3)
This is the proper theory and equation behind my calculations below.
Here are the answers for 5) c) as requested:
i) Moles of C4H6: 0.02/24=0.000833
From equation, we know 2 moles of C4H6 reacts with 11 moles of O2
Therefore, moles of O2: 0.000833*5.5=0.00458
Therefore, volume of O2: 4.58*24*1000=110cm3
ii) From equation, we know 2 moles of C4H6 produces 8 moles of CO2
Therefore, moles of CO2: 0.000833*4=0.00333
Therefore, volume of CO2: 0.00333*24*1000=80cm3
iii) From equation, we know 2 moles of C4H6 produces 6 moles of H2O
Therefore, moles of H2O: 0.000833*3=0.0025
Therefore, volume of H2O: 0.0025*24*1000=60
Therefore, total volume of gases is simply volume of CO2 + volume of H2O:
80+60=140cm3
Alternatively, 8+6=14, so 2 moles of C4H6 produces 14 moles of products
Therefore, moles of products: 0.000833*7=0.00583
Therefore, volume of products: 0.00583*24*1000=140cm3
For part d), you use this formula:
Mass
Moles = ------
Mr
d) From the above equation, 1 mole of butyne forms 3 moles of water
Number of moles of butyne reacted: 9/54=0.167
Number of moles of water formed: 0.167*3=0.5
Mass of water formed: 0.5*(2+16)=9g
I hope this has helped. :D
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All of Q5 has been answered previously, I hope this is good enough, obviously not the mark scheme though! :D
hahaha. thanks, ;)
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HOW DO YOU DRAW FREE MOVING ELECTRONS IN AN ALLOY? :o
do you draw '-' signs in the atoms? Lol xD
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HOW DO YOU DRAW FREE MOVING ELECTRONS IN AN ALLOY? :o
do you draw '-' signs in the atoms? Lol xD
This website gives a good explanation about structure of alloys. Enjoy :P
http://www.gcsescience.com/ex29.htm (http://www.gcsescience.com/ex29.htm)
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Can someone show his way of calculation for this Question, plz :D
-
Can someone show his way of calculation for this Question, plz :D
OK right, here goes:
i) Moles of butane: 0.01/24=0.000417
From the equation, 1 mole of butane reacts with 6.5 moles of oxygen
Therefore, 0.000417*6.5=0.00271
So volume of oxygen reacted: 0.00271*24*1000=65cm3
Therefore, volume of oxygen left: 100-65=35cm3
ii) From the equation, 1 mole of butane gives 4 moles of carbon dioxide
Therefore, 0.000417*4=0.00167
So volume of carbon dioxide formed: 0.00167*24*1000=40cm3
That was the technical way of doing it. Here is a simply way, but only applies if calculations involve gases only:
Consider this formula:
Volume of gas (in dm3)
Moles of gas = --------------------------
24
Because we know one mole of gas occupies 24dm3 at r.t.p., therefore we can go about it this way:
i) From the equation, 1 mole of butane reacts with 6.5 moles of oxygen
So, 10cm3 of butane reacts with 10*6.5=65cm3 of oxygen
Therefore, volume of oxygen left: 100-65=35cm3
ii) From the equation, 1 mole of butane gives 4 moles of carbon dioxide
So 10cm3 of butane gives 10*4=40cm3 of carbon dioxide
However, the way I've gone about it using ratios can only be applied to gas volumes calculations, as explained above. For a lot of the others, you'll still need to apply the formula:
Mass
Moles = ------
Mr
If you still don't get it, let me know! :D
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people there is smthn i wanna kno ........when r hydrocarbons solids , and when r they liquid and when r they gases? ....
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people there is smthn i wanna kno ........when r hydrocarbons solids , and when r they liquid and when r they gases? ....
Usually, small chained hydrocarbons are gases, and the state changes from gas to liquid to solid as the chain length increases.
Eg: methane--> gas
hexane--> liquid
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Usually, small chained hydrocarbons are gases, and the state changes from gas to liquid to solid as the chain length increases.
Eg: methane--> gas
hexane--> liquid
thx :)
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people there is smthn i wanna kno ........when r hydrocarbons solids , and when r they liquid and when r they gases? ....
Boiling point increases with chain length. So for example, for alkanes:
Methane: -164OC
Ethane: -87OC
Propane: -42OC
Butane: -0.5OC
First four alkanes - gases at room temperature.
Next twelve are liquids.
The rest are solids.
The explanation for this is that as chain length increases, the attraction between the molecules increases - so it takes more energy to separate them.
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Boiling point increases with chain length. So for example, for alkanes:
Methane: -164OC
Ethane: -87OC
Propane: -42OC
Butane: -0.5OC
that's gd info , thx man :D
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OK right, here goes:
i) Moles of butane: 0.01/24=0.000417
From the equation, 1 mole of butane reacts with 6.5 moles of oxygen
Therefore, 0.000417*6.5=0.00271
So volume of oxygen reacted: 0.00271*24*1000=65cm3
Therefore, volume of oxygen left: 100-65=35cm3
ii) From the equation, 1 mole of butane gives 4 moles of carbon dioxide
Therefore, 0.000417*4=0.00167
So volume of carbon dioxide formed: 0.00167*24*1000=40cm3
That was the technical way of doing it. Here is a simply way, but only applies if calculations involve gases only:
Consider this formula:
Volume of gas (in dm3)
Moles of gas = --------------------------
24
Because we know one mole of gas occupies 24dm3 at r.t.p., therefore we can go about it this way:
i) From the equation, 1 mole of butane reacts with 6.5 moles of oxygen
So, 10cm3 of butane reacts with 10*6.5=65cm3 of oxygen
Therefore, volume of oxygen left: 100-65=35cm3
od tho
ii) From the equation, 1 mole of butane gives 4 moles of carbon dioxide
So 10cm3 of butane gives 10*4=40cm3 of carbon dioxide
However, the way I've gone about it using ratios can only be applied to gas volumes calculations, as explained above. For a lot of the others, you'll still need to apply the formula:
Mass
Moles = ------
Mr
If you still don't get it, let me know! :D
thanks so much i also had this doubt. i dont get the second method tho :/ can u explain it further cuz it seems so simple :P
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thanks so much i also had this doubt. i dont get the second method tho :/ can u explain it further cuz it seems so simple :P
The first method is guaranteed to work. However, the second way to do it, only for gases, I suppose is because 1 mole of gas occupies the same volume, at the same temperature and pressure. At temperature and pressure, this volume is 24dm3.
So I suppose because the formula for finding out moles is: volume/24. Because this 24 is a constant value when working out the number of moles for a gas, then you could just look at the volumes of gas used and the ratio in the equations, as the ratio would be the same.
However, for things like working out concentration, the moles of the substance using the formula varies, and not at 24, so I guess that's why it can be so simply done for gas calculations.
I hope that clears your doubt somewhat.
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The first method is guaranteed to work. However, the second way to do it, only for gases, I suppose is because 1 mole of gas occupies the same volume, at the same temperature and pressure. At temperature and pressure, this volume is 24dm3.
So I suppose because the formula for finding out moles is: volume/24. Because this 24 is a constant value when working out the number of moles for a gas, then you could just look at the volumes of gas used and the ratio in the equations, as the ratio would be the same.
However, for things like working out concentration, the moles of the substance using the formula varies, and not at 24, so I guess that's why it can be so simply done for gas calculations.
I hope that clears your doubt somewhat.
somewhat :P thanks anyway :)
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@ Ivo i found this in the examiner's report
Question 7
(a) (i) Candidates did not seem to be familiar with this type of calculation and did not realise that the mole
ratio for gases is the same as the reacting volume ratio. With this knowledge, the calculation is
easy and involves some simple arithmetic.
butane oxygen
mole ratio 1 6.5
volume ratio 10 65
Therefore 65 cm3 of oxygen used. 100 – 65 = 35 cm3 left.
By the same reasoning, 10 cm3 of butane will form 40 cm3 of carbon dioxide.
you're right and i get it :D
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@ Ivo i found this in the examiner's report
Question 7
(a) (i) Candidates did not seem to be familiar with this type of calculation and did not realise that the mole
ratio for gases is the same as the reacting volume ratio. With this knowledge, the calculation is
easy and involves some simple arithmetic.
butane oxygen
mole ratio 1 6.5
volume ratio 10 65
Therefore 65 cm3 of oxygen used. 100 – 65 = 35 cm3 left.
By the same reasoning, 10 cm3 of butane will form 40 cm3 of carbon dioxide.
you're right and i get it :D
Gosh, that one sentance from the examiner's report explained 3 paragraphs of what I said! I really need to work on explaining consisely! ;P
By the way, which session/year was this question from?
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Heyy guys I need some help in the acids bases chapter.
Describe and explain the importance of controlling acidity in soil.
Is it just that different plants require different acidity for growth. Can anyone please explain a little more?
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Heyy guys I need some help in the acids bases chapter.
Describe and explain the importance of controlling acidity in soil.
Is it just that different plants require different acidity for growth. Can anyone please explain a little more?
Soil may become acidic after a number of years. This can be due to acid rain, bacteria and fungi rotting the vegetation so that it releases acids or use of fertilisers containing ammonium salts.
Many crop plants such as onions, cabbage and beans grow better if the soil is neutral. If soil acidity drow below pH 5.5 many plants will not grow well.
We can remove excess acidity from the soil by adding crushed limestone - calcium carbonate. This neutralises the acid. The calcium carbonate and the products are neutral.
CaCO3 + 2H+ -> Ca2+ + CO2 + H2O
Farmers often add lime (calcium oxide) to the soil. This also neutralises excess acid.
CaO + 2H+ -> Ca2+ + H2O
However, care must be taken to ensure not too much lime is added to the soil. This is because lime is strongly alkaline when it dissolves in water. Most plants do not survive alkaline conditions. Therefore, if the soil does become too alkaline, farmers spray the soil with manure or even with very dilute sulphuric acid.
I hope this has cleared your doubt. ;)
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OK right, here goes:
i) Moles of butane: 0.01/24=0.000417
From the equation, 1 mole of butane reacts with 6.5 moles of oxygen
Therefore, 0.000417*6.5=0.00271
So volume of oxygen reacted: 0.00271*24*1000=65cm3
Therefore, volume of oxygen left: 100-65=35cm3
ii) From the equation, 1 mole of butane gives 4 moles of carbon dioxide
Therefore, 0.000417*4=0.00167
So volume of carbon dioxide formed: 0.00167*24*1000=40cm3
That was the technical way of doing it. Here is a simply way, but only applies if calculations involve gases only:
Consider this formula:
Volume of gas (in dm3)
Moles of gas = --------------------------
24
Because we know one mole of gas occupies 24dm3 at r.t.p., therefore we can go about it this way:
i) From the equation, 1 mole of butane reacts with 6.5 moles of oxygen
So, 10cm3 of butane reacts with 10*6.5=65cm3 of oxygen
Therefore, volume of oxygen left: 100-65=35cm3
ii) From the equation, 1 mole of butane gives 4 moles of carbon dioxide
So 10cm3 of butane gives 10*4=40cm3 of carbon dioxide
However, the way I've gone about it using ratios can only be applied to gas volumes calculations, as explained above. For a lot of the others, you'll still need to apply the formula:
Mass
Moles = ------
Mr
If you still don't get it, let me know! :D
Thank you so much ;D
I fully understand now thanks to you :D
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Gosh, that one sentance from the examiner's report explained 3 paragraphs of what I said! I really need to work on explaining consisely! ;P
By the way, which session/year was this question from?
2008 O/N first variant,
Althought i prefer the first method u explained, there might be enough place for
many calculations
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2008 O/N first variant,
Althought i prefer the first method u explained, there might be enough place for
many calculations
In which case the 2nd method is probably more straight-forward and less time consuming. I just included the 1st method so that you guys can understand it completely! :D
You could always use the blank pages for rough working.
I guess the key idea for the 2nd method, nicely provided by Dana is:
The mole ratio for gases is the same as the reacting volume ratio.
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can somebody answer this and explain to me pls? ???
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can somebody answer this and explain to me pls? ???
OK, Q24, we know that it is a sensory neurone so it must be D. We know it's the sensory neurone because it has a long dendron and short axon. Dendron bring information to the cell body, and axon bring information away from the cell body. Also, the cell body is located outside the spinal cord, so we know it is a sensory neurone.
Q28, I think it's C, because it's developing because there is a vacuole. Also, it is growing because cell number is increasing.
Q38, B, think of the log phase, exponential, because there are no limiting factors, so everything is in abundance (e.g. unlimited space, food etc)
Did I get them right?
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Heyy Ivo thanks for ur help man!
Just something i wanna add to that...they add peat (manure) to make the soil acidic, as well as acid! XD
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OK, Q24, we know that it is a sensory neurone so it must be D. We know it's the sensory neurone because it has a long dendron and short axon. Dendron bring information to the cell body, and axon bring information away from the cell body. Also, the cell body is located outside the spinal cord, so we know it is a sensory neurone.
Q28, I think it's C, because it's developing because there is a vacuole. Also, it is growing because cell number is increasing.
Q38, B, think of the log phase, exponential, because there are no limiting factors, so everything is in abundance (e.g. unlimited space, food etc)
Did I get them right?
yup...u got them right again...thx for the explanation bro...
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Thanks
-
HELP PLEASE!
bii) & d) ! :D :D :D :D
thaaaanks.
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Another isomer would be :
CH3-CH=CH-CH3 Name= But-2-ene
For part (d)
monomer is propene CH3-CH=CH2
-
Another isomer would be :
CH3-CH=CH-CH3 Name= But-2-ene
... explanation ? :(
-
... explanation ? :(
Okay first look at the alkene. How many carbons are there ? 4, right ? So that means it is butene OR Butane.
BUT it has a carbon double bond so it must be an ALKENE hence it is BUTENE !!
Now the isomer of butene can be but-2-ene. The numeral 2 signifies that the carbon double bond is located on the SECOND CARBON.
So thats how you do it :)
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Okay first look at the alkene. How many carbons are there ? 4, right ? So that means it is butene OR Butane.
BUT it has a carbon double bond so it must be an ALKENE hence it is BUTENE !!
Now the isomer of butene can be but-2-ene. The numeral 2 signifies that the carbon double bond is located on the SECOND CARBON.
So thats how you do it :)
thank you. how do you draw dii) ?
By the way... 'The numeral 2 signifies that the carbon double bond is located on the SECOND CARBON' ? um.. from the right? O.o
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thank you. how do you draw dii) ?
By the way... 'The numeral 2 signifies that the carbon double bond is located on the SECOND CARBON' ? um.. from the right? O.o
https://studentforums.biz/index.php/topic,8531.15.html Read to learn how to name. He is referring to an alkane on the 1st page.
dii) BELOW
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https://studentforums.biz/index.php/topic,8531.15.html Read to learn how to name. He is referring to an alkane on the 1st page.
dii) BELOW
thanks. how do we join 3 of those together? like.. 3 units together? :/
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thanks. how do we join 3 of those together? like.. 3 units together? :/
I dont understand. ???
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He meant how to join three units of monomers?
and By the way+rep.
Thanks :)
Oh, okay. Just remove the brackets and repeat my drawing 3 time making sure the bonds on the side connect to each consecutive unit.
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Thanks :)
Oh, okay. Just remove the brackets and repeat my drawing 3 time making sure the bonds on the side connect to each consecutive unit.
hahah lol okay thanks :)
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hahah lol okay thanks :)
Any time ! ;)
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i really dont understand anything in moles......can some1 gimme a site where they explain how to calculate moles easily? thanks.
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i really dont understand anything in moles......can some1 gimme a site where they explain how to calculate moles easily? thanks.
http://thenightdreamer.wordpress.com/2010/03/19/moles/
The link takes you to my website. It may help you.
Like I said post a question you dont understand and we'll help you ;)
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Thanks
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guys this question is freaking me out ( it is from igcse study guide for chemistry ,
about stoichiometry pg31
sample q 5
calcaluate the volume of sodium hydroxide , concentration of 0.16 mol/dm3 , needed to neutralise 20 cm3
of sulphric acid , concentration 0.2 mol/dm3 .
the eqation is 2NaOH+H2SO4--->Na2SO4+H20
-------------------------------------------------------
the answer is moles of H2SO4 = 20 divided by 10000 * 0.2 = 0.004
?????
know why divided by 10000 ??????????????????????????? ??? :-\
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to convert cm3 to dm3 (decimeter cube) ... dm3 is used ALWAYS ;)
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to convert cm3 to dm3 (decimeter cube) ... dm3 is used ALWAYS ;)
yea but isn't 1dm3=1000cm3
so 20cm3 *1dm3 divided by 1000 will not give 10000dm3 ?????
???
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guys this question is freaking me out ( it is from igcse study guide for chemistry ,
about stoichiometry pg31
sample q 5
calcaluate the volume of sodium hydroxide , concentration of 0.16 mol/dm3 , needed to neutralise 20 cm3
of sulphric acid , concentration 0.2 mol/dm3 .
the eqation is 2NaOH+H2SO4--->Na2SO4+H20
-------------------------------------------------------
the answer is moles of H2SO4 = 20 divided by 10000 * 0.2 = 0.004
?????
know why divided by 10000 ??????????????????????????? ??? :-\
Moles of sulphuric acid = 0.2*0.02=0.004
Moles of sodium hydroxide = 0.004*2=0.008
Volume of sodium hydroxide = 0.008/0.16=0.05dm3 or 50cm3
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yea but isn't 1dm3=1000cm3
so 20cm3 *1dm3 divided by 1000 will not give 10000dm3 ?????
???
Since it's from a textbook, there are always typos :P. I can confirm to convert cm3 to dm3, you divide by 1000. So the book is wrong :D
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Moles of sulphuric acid = 0.2*0.02
Moles of sodium hydroxide = 0.02*2=0.04
Volume of sodium hydroxide = 0.04/0.16=0.25dm3
THX BUT THE ANSWER IN MY BOOK SAYS O.05 DM3 AND U ANSWER WILL BE 0.25?
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THX BUT THE ANSWER IN MY BOOK SAYS O.05 DM3 AND U ANSWER WILL BE 0.25?
Sorry my mistake. I've edited the post.
Moles of sulphuric acid = 0.2*0.02=0.004
Moles of sodium hydroxide = 0.004*2=0.008
Volume of sodium hydroxide = 0.008/0.16=0.05dm3 or 50cm3
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Sorry my mistake. I've edited the post.
Exactly I was kinda wondering ...
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THX :D
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I've included some information about salt preparations, I hope this is useful for you.
-
I've included some information about salt preparations, I hope this is useful for you.
Thanks for this dude!!! ;)
ur awsum!!...=D
:D :D
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i have a quick question the formula for acids is cnh2n+1 cooh but i read that there is a new formula which works the same cnh2n o2 how can it be the same
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i have a quick question the formula for acids is cnh2n+1 cooh but i read that there is a new formula which works the same cnh2n o2 how can it be the same
I don't see how the second one can possibly work. It is definitely CnH2n+1COOH.
The functional group is -COOH so I can't see how that can change.
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the functional group is -COOH.... sometimes written as -CO2H... and how would that work? CnH2nO2? that would remove one the hydrogens...
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i have a quick question the formula for acids is cnh2n+1 cooh but i read that there is a new formula which works the same cnh2n o2 how can it be the same
the correct forumla of acid is Cn-1 H2n-1COOH
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I have an important question and it is expected to come in the chemistry paper 3
-describe the use of hydrogen as a potential fuel reacting with oxygen to generate electricity in a fuel cell ??
is this is new ,, i never saw a quetion in the past papers about this topic, if there is any quetion in the pastpapers plz post it here !!
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the correct forumla of acid is Cn-1 H2n-1COOH
I don't think there's a -1. I think this is it:
CnH2n+1COOH
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I don't think there's a -1. I think this is it:
CnH2n+1COOH
yup that's right.
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I have an important question and it is expected to come in the chemistry paper 3
-describe the use of hydrogen as a potential fuel reacting with oxygen to generate electricity in a fuel cell ??
is this is new ,, i never saw a quetion in the past papers about this topic, if there is any quetion in the pastpapers plz post it here !!
There would not be any past paper questions for this particular topic as it is new for the 2010 syllabus (any new material for the 2010 syllabus is highlighted by black veritcal lines either side of the text.
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I have an important question and it is expected to come in the chemistry paper 3
-describe the use of hydrogen as a potential fuel reacting with oxygen to generate electricity in a fuel cell ??
is this is new ,, i never saw a quetion in the past papers about this topic, if there is any quetion in the pastpapers plz post it here !!
It's a potential fuel cause it is non-polluting. The products of the reaction in the cell is water. It also has a high efficiency and requires less maintenance.
-
There would not be any past paper questions for this particular topic as it is new for the 2010 syllabus (any new material for the 2010 syllabus is highlighted by black veritcal lines either side of the text.
Because the syllabus also says: details of the construction and operation of a fuel cell are not required
I guess the key points you would need to know is:
1) A hydrogen-oxygen fuel cell produces only water as a product.
2) A hydrogen-oxygen fuel cell is efficient and non-polluting.
3) When a fuel cell is working, hydrogen loses electrons at the cathode and oxygen gains electrons at the anode.
Here's a nice diagram! ;)
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There would not be any past paper questions for this particular topic as it is new for the 2010 syllabus (any new material for the 2010 syllabus is highlighted by black veritcal lines either side of the text.
... The IGCSE Chemistry Revision Guide, which was published in 2006 / 2007, has devoted a page to hydrogen fuel cells :o
Would it be considered as copyright infringement if I were to scan and upload that particular page ?
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... The IGCSE Chemistry Revision Guide, which was published in 2006 / 2007, has devoted a page to hydrogen fuel cells :o
Would it be considered as copyright infringement if I were to scan and upload that particular page ?
Nope ;)
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Nope ;)
Hydrogen fuel cells
Advantages :
- Most energy rich (releases more energy per kg than any other conventional fuel)
- Only product of combustion is water
- Oxides of nitrogen are not produced
Disadvantages :
- Difficult to store
- Expensive to produce
H2 -> 2H+ + 2e-
O2 + 2H2O + 4e- -> 4OH-
H+ + OH- -> H2O
2H2 + O2 > 2H2O
-
Because the syllabus also says:
I guess the key points you would need to know is:
1) A hydrogen-oxygen fuel cell produces only water as a product.
2) A hydrogen-oxygen fuel cell is efficient and non-polluting.
3) When a fuel cell is working, hydrogen loses electrons at the cathode and oxygen gains electrons at the anode.
Here's a nice diagram! ;)
I believe u have reversed them, hydrogen at the anode nd oxygen at da cathode.
This is opposite of electrolysis. It's shown by ur diagram even...!
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I believe u have reversed them, hydrogen at the anode nd oxygen at da cathode.
This is opposite of electrolysis. It's shown by ur diagram even...!
Hmm, I'm pretty sure reaction invovling hydrogen happens at cathode and likewise for oxygen at the anode. I guess the diagram I chose was a bit weird, because if you look carefully, there are the - sign in hydrogen and + in oxygen.
My 'case' for this is also exemplified by this link:
http://inventors.about.com/od/sstartinventions/ss/Physics_Illustr_2.htm (http://inventors.about.com/od/sstartinventions/ss/Physics_Illustr_2.htm)
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I believe u have reversed them, hydrogen at the anode nd oxygen at da cathode.
This is opposite of electrolysis. It's shown by ur diagram even...!
See this diagram. I found it pretty good. :)
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Guys a stupid doubt ... How to name this? I seriously forgot :-[
-
I think it's 2-3 methylpentane
Not sure.. :-\
-
I think it's 2-3 methylpentane
Not sure.. :-\
I think its 2 -3 dimethylpentane
-
2,3- dimethylpentane
-
2,3-dimethylpentane it is
-
2,3-dimethylpentane it is
Score one for the home team !!!!!!! :P
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http://www.xtremepapers.net/CIE/Cambridge%20IGCSE/0620%20-%20Chemistry/0620_s09_qp_3.pdf (http://www.xtremepapers.net/CIE/Cambridge%20IGCSE/0620%20-%20Chemistry/0620_s09_qp_3.pdf)
Can anyone explain me 6)b) ??? ???
Thanks
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6)b) i) equlibrium occurs wen the amount of the reactants are equal to the amount of the product. Also it is wen the rate of the forward and backward reactions are the same
forward reaction is wen nitrogen and hydrogen react to form ammonia
backward reaction is wen the ammonia breaks up into nitrogen and hydrogen
ii) according to the graph an increase in temperature causes a decrease in the % of ammonia
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6)b) i) equlibrium occurs wen the amount of the reactants are equal to the amount of the product. Also it is wen the rate of the forward and backward reactions are the same
forward reaction is wen nitrogen and hydrogen react to form ammonia
backward reaction is wen the ammonia breaks up into nitrogen and hydrogen
ii) according to the graph an increase in temperature causes a decrease in the % of ammonia
omg man srryyy i meant 5)b... really sorry :P
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can somebooooody tell me about liver cell???
-
can somebooooody tell me about liver cell???
liver cell is the normal animal cell having cytoplasm, a nucleus and a cell membrane.
-
liver cell is the normal animal cell having cytoplasm, a nucleus and a cell membrane.
only???????????
nothing different???
whats the function?
-
only???????????
nothing different???
whats the function?
nope i dont think there is anything different abt it unless u have to compare it to a plant cell or bacterial cell etc
i dont think they will ask the function of a liver cell...they can ask the function of the liver, not the cell.
heres a site fr the functions of the liver
http://www.essortment.com/all/liverscellsstr_ricl.htm
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omg man srryyy i meant 5)b... really sorry :P
no problem.. ;)
anyways
the vol. of phosphate soln used in cm3 is half the height of the ppt in mm
also at 8cm3 all the soln is used up. tht is because adding more does not increase the height of the ppt meaning there was no further reaction on adding more.
also the formula is T3(PO4)2-----because
u take it as 12cm3 of T nitrate react with 8cm3 of sodium phosphate (thts wen all the reactants r used up)
so.....12:8...simplify it
12:8
6:4
3:2
and therefore u get T3(PO4)2
-
no problem.. ;)
anyways
the vol. of phosphate soln used in cm3 is half the height of the ppt in mm
also at 8cm3 all the soln is used up. tht is because adding more does not increase the height of the ppt meaning there was no further reaction on adding more.
also the formula is T3(PO4)2-----because
u take it as 12cm3 of T nitrate react with 8cm3 of sodium phosphate (thts wen all the reactants r used up)
so.....12:8...simplify it
12:8
6:4
3:2
and therefore u get T3(PO4)2
Thank you for the explanation :D
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nope i dont think there is anything different abt it unless u have to compare it to a plant cell or bacterial cell etc
i dont think they will ask the function of a liver cell...they can ask the function of the liver, not the cell.
heres a site fr the functions of the liver
http://www.essortment.com/all/liverscellsstr_ricl.htm
thx dude
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can somebooooody tell me about liver cell???
Because it is only a Biology Paper 1, you won't even really need to know about functions of the cell structures, because this is extension material (for Paper 3).
What you do need to know is the differences between plant and animal cells. From looking at many past papers, CIE seem to like the liver cell as a typical animal cell and a palisade cell as a typical plant cell. Those two are typical, so you should have no trouble identifying which is which! :P
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what is meant by a limiting reagent ?
and in fermentation what is the catalyst used ??
-
what is meant by a limiting reagent ?
and in fermentation what is the catalyst used ??
When we carry out a reaction we sometimes use an excess of one of the reactants. The reactant that is not in excess is called the limiting reactant or limiting reagent. Basically, the reaction stops when the limiting reactant is used up.
The bacteria and yeasts produce enzymes that catalyse fermentation reactions in organic materials.
I hope I have answered your questions. ;)
-
what is meant by a limiting reagent ?
and in fermentation what is the catalyst used ??
they use me as a catalyst! :P
-
Because it is only a Biology Paper 1, you won't even really need to know about functions of the cell structures, because this is extension material (for Paper 3).
What you do need to know is the differences between plant and animal cells. From looking at many past papers, CIE seem to like the liver cell as a typical animal cell and a palisade cell as a typical plant cell. Those two are typical, so you should have no trouble identifying which is which! :P
thx man...
-
hmm.......
i think the answer should be D
By the way wat does the mark scheme say?
-
can some1 send me all they can (through message) on these subjects PLEASE ??? :-\
1-Ionic, Covelent and micro structures
2-Formulae of Fats,Carbohydrates,Proteins
3-Hydrocarbon Reaction
Thank Ya'll!
-
can some1 send me all they can (through message) on these subjects PLEASE ??? :-\
1-Ionic, Covelent and micro structures
2-Formulae of Fats,Carbohydrates,Proteins
3-Hydrocarbon Reaction
Thank Ya'll!
check this link , i hope i t helps :
https://studentforums.biz/index.php/topic,8469.0.html
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Question: Why might pesticides sprayed onto the fields reduce a bean crop?
Answer Choices:
A Pesticides damage plant leaves.
B Pesticides damage plant roots.
C Pesticides kill insects that feed on bean plants.
D Pesticides kill insects that pollinate bean plants.
Isn't this a badly worded question?
What would you guys pick as the answer?
The answer is D. This is cause pesticides affect ONLY the pests, and not the plant. So due to this the first two options are eliminated.. :) and C is true but tht ans has no reason as to WHY it affects the bean crop. AND D, makes sense cause if the insects are killed and if the plant uses insect- pollination methods, then killing the insects will have an effect on the bean crop. So D is the ans. Hope u have understood.. :)
-
Outline how hydrogen is manufactured from water ???
Do i just say electrolysis
-
Outline how hydrogen is manufactured from water ???
Do i just say electrolysis
electrolysis of CONCENTRATED AQUEOUS SODIUM CHLORIDE.
-
Electrolysis of Brine or water...anything is fine
-
Only, ok i thought electrolysis of water (voltameter) but thats
too expensive in factories. What i thought was wrong :-\
Thanks ;D
Ari and Nid
-
The answer is D. This is cause pesticides affect ONLY the pests, and not the plant. So due to this the first two options are eliminated.. :) and C is true but tht ans has no reason as to WHY it affects the bean crop. AND D, makes sense cause if the insects are killed and if the plant uses insect- pollination methods, then killing the insects will have an effect on the bean crop. So D is the ans. Hope u have understood.. :)
Yes, indeed, the only answer has to be D. For C, it will actually increase bean crops not reduce it! Because normally pesticides kill pests, so less pests, more crops. But the question is, what can reduce the bean crop. So it has to be D, indeed Raywin is correct.
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Outline how hydrogen is manufactured from water ???
Do i just say electrolysis
Brine is electrolysed in a diaphragm cell.
The ions in solution are Na+, H+, Cl- and OH-.
At the anode: chloride ions lose electrons and are discharged as chlorine gas:
2Cl- -> Cl2 + 2e-
At the cathode: hydrogen ions accept electrons and hydrogen gas is discharged rather than sodium:
2H+ +2e- -> H2
The ions remaining in solution are Na+ and OH-. So an aqueous solution of sodium hydroxide is formed.
-
+rep Ivo ;)
Good Job !
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how does electrostatic dust precipitator removes charged particles from sulphur dioxide ??? ??? ??? ???
thanz
-
how does electrostatic dust precipitator removes charged particles from sulphur dioxide ??? ??? ??? ???
thanz
wtf is that :D ;D xD
-
Brine is electrolysed in a diaphragm cell.
The ions in solution are Na+, H+, Cl- and OH-.
At the anode: chloride ions lose electrons and are discharged as chlorine gas:
2Cl- -> Cl2 + 2e-
At the cathode: hydrogen ions accept electrons and hydrogen gas is discharged rather than sodium:
2H+ +2e- -> H2
The ions remaining in solution are Na+ and OH-. So an aqueous solution of sodium hydroxide is formed.
any idea y is it called diaphragm cell?
-
any idea y is it called diaphragm cell?
Maybe because there is a porous membrane (a.k.a. diaphragm) separating the anode and cathode, I guess.
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Brine is electrolysed in a diaphragm cell.
The ions in solution are Na+, H+, Cl- and OH-.
At the anode: chloride ions lose electrons and are discharged as chlorine gas:
2Cl- -> Cl2 + 2e-
At the cathode: hydrogen ions accept electrons and hydrogen gas is discharged rather than sodium:
2H+ +2e- -> H2
The ions remaining in solution are Na+ and OH-. So an aqueous solution of sodium hydroxide is formed.
Thanks Ivo u summed it up :D
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Why does the melting point, boiling point and density increase as you go down a group?
And is this statement true for all the groups [metals and non-metals]?
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Why does the melting point, boiling point and density increase as you go down a group?
And is this statement true for all the groups [metals and non-metals]?
It really depends on which group you're talking about.
Group I metals: the melting and boling points decrease down the group.
Group VII elements: the melting and boiling points of the halogens increase down the group. This is the opposite trend to the Group I metals.
I believe those are the 2 trends you need to know for IGCSE.
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It really depends on which group you're talking about.
Group I metals: the melting and boling points decrease down the group.
Group VII elements: the melting and boiling points of the halogens increase down the group. This is the opposite trend to the Group I metals.
I believe those are the 2 trends you need to know for IGCSE.
OK, why is there this difference, I mean why is it that the melting and boiling point in Group I decrease as you go down the group and increase as you go up Group VII? Has this got something to do with their valence electrons? Can you please explain that a little further?
Thank you so much :)
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^First you need to understand bonding in metals. Each metal atom loses its outer electrons, which are then free to move between the lattice of positively charged metal ions in the solid. The metal ions are held in a rigid formation by the force of attraction between the positive ions and the 'sea' of negative electrons surrounding them. As you go down group 1, however, the atoms become larger so that the positive nucleus gets further away from the negative sea of electrons. The force of attraction between the metal ions and the sea of electrons thus gets weaker down the group and the melting points decrease as less heat energy is needed to overcome this weakening force of attraction.
I hope this makes sense.
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OK, why is there this difference, I mean why is it that the melting and boiling point in Group I decrease as you go down the group and increase as you go up Group VII? Has this got something to do with their valence electrons? Can you please explain that a little further?
Thank you so much :)
By the way, we only need to know the trends for Group I and IV for b.p.s and m.p.s.
Right. First you need to understand bonding in metals. Each metal atom loses its outer electrons, which are then free to move between the lattice of positively charged metal ions in the solid. The metal ions are held in a rigid formation by the force of attraction between the positive ions and the 'sea' of negative electrons surrounding them. As you go down the group, however, the atoms become larger so that the positive nucleus gets further away from the negative sea of electrons. The force of attraction between the metal ions and the sea of electrons thus gets weaker down the group and the melting points decrease as less heat energy is needed to overcome this weakening force of attraction.
For Group IV, as you go down the group, the molecules get bigger, so the atomic radius increases as the number of electrons increase. Because halogens exist as diatomic molecules, they have intermolecular forces (of the Van der Waals dispersion forces). So when the molecules are bigger, there is an increase in the chances for setting up temporary dipoles - which causes these attractive forces. So the stronger the attractive forces, the more energy required to break these bonds, so m.p. and b.p. increases.
I have to stress however that at IGCSE you do not need to know why any of these trends happen. You simply need to know what the trends are. So don't worry if all this jargon doesn't make sense to you right now, more will become clear if and when you study AS Chemistry.
Anyway, hope I answered your question clearly enough. ;D
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^First you need to understand bonding in metals. Each metal atom loses its outer electrons, which are then free to move between the lattice of positively charged metal ions in the solid. The metal ions are held in a rigid formation by the force of attraction between the positive ions and the 'sea' of negative electrons surrounding them. As you go down group 1, however, the atoms become larger so that the positive nucleus gets further away from the negative sea of electrons. The force of attraction between the metal ions and the sea of electrons thus gets weaker down the group and the melting points decrease as less heat energy is needed to overcome this weakening force of attraction. The opposite applies to Group VII.
I hope that makes sense.
LOLS, no! the Group IV elements aren't metals. If you're gonna copy and paste at least think! So halogens don't have a 'sea' of electrons or positive ions, just think for a minute! :P
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Hm...I actually understood it that way. I totally missed the fact that were talking about non-metals. The copied part is actually right for the record, my addition was wrong. If you're going to elaborate, don't quote the whole thing since it's true.
Oh right, you got that as well, what a coincidence.
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Thanks a lot Lariemeeva and Ivo for your help!
You've both done a great job!
THANK YOU ;D
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Hm...I actually understood it that way. I totally missed the fact that were talking about non-metals. The copied part is actually right for the record, my addition was wrong. If you're going to elaborate, don't quote the whole thing since it's true.
Oh right, you got that as well, what a coincidence.
LOL, what a coincidence! I didn't mean to criticse you in a bad way. No hard feelings OK? I hope I haven't caused anyone to be upset. :-\
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somebody help me with this...
to answer first question u need the pic(attached)...
i dont understand this.... :'(
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somebody help me with this...
to answer first question u need the pic(attached)...
i dont understand this.... :'(
For your first question, I think the answer would be C where osmosis happens at X and transpiration happens at Y.
The arrow at X points at a cell, and the question tells you that the plant is losing water, so water loss from the cell takes place only by osmosis. And C is the only option with Osmosis taking place at X.
I'm not really sure about your second question, I prefer leaving it to someone who knows it better.
By the way, which year are these questions from?
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somebody help me with this...
to answer first question u need the pic(attached)...
i dont understand this.... :'(
For your first question, I think the answer is B. Because at X, water evaporates and becomes water vapour. Then at Y, the water vapour diffuses out into the atmosphere.
I suppose for your second question the answer is B because it has to be either B or D, because the animal is immersed in the indicator, so the carbon dioxide produced from respiration doesn't have to tavel a great distance to reach the paper. It has to be B because in D, the indicator paper is larger so obviously it would take longer to change colour.
Did I get it right?
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For your first question, I think the answer is B. Because at X, water evaporates and becomes water vapour. Then at Y, the water vapour diffuses out into the atmosphere.
I suppose for your second question the answer is B because it has to be either B or D, because the animal is immersed in the indicator, so the carbon dioxide produced from respiration doesn't have to tavel a great distance to reach the paper. It has to be B because in D, the indicator paper is larger so obviously it would take longer to change colour.
Did I get it right?
Yeah both the answers are B. you are right.. :)
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Hey guys, doubt.. :-\ cant figure out the parts (iii) and (iv). The Q is attached. :) Thanks a lot in advance... ;D
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For your first question, I think the answer is B. Because at X, water evaporates and becomes water vapour. Then at Y, the water vapour diffuses out into the atmosphere.
I suppose for your second question the answer is B because it has to be either B or D, because the animal is immersed in the indicator, so the carbon dioxide produced from respiration doesn't have to tavel a great distance to reach the paper. It has to be B because in D, the indicator paper is larger so obviously it would take longer to change colour.
Did I get it right?
yup...right again ;)
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Hey guys, doubt.. :-\ cant figure out the parts (iii) and (iv). The Q is attached. :) Thanks a lot in advance... ;D
Okay, I'll start with i)
a)
i)D :2,8,18,8 - stable
ii)E :2,8,18,8,1 - Group-I metal, one of the property:low density
iii) Covalent means two non-metals..so select only non-metals from the table..(except A) B- 2,8,4 and F 2,8,18,18,7
try to bond A with both of them (by drawing the atomic structure)
It is not possible with B, so it has to be F
OR if you want to be sure of your answer draw the bonding between A and F, gives you AF3
iv)its B, always giant covalent structure of diamond has 4 electrons in the valence shell(outermost shell). Hence B
Revise Structure of diamond ;)
v) A
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Does this mean that ONLY water moves by osmosis? Even water VAPOR has to move by diffusion? Because I picked osmosis for that one, but yeah I guess, even water vapor must move by diffusion right? ONLY water and NOTHING else moves by osmosis?
yes, water moves only by osmosis through a semi-permeable membrane. Water vapor moves by diffusion and not osmosis
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Okay, I'll start with i)
a)
i)D :2,8,18,8 - stable
ii)E :2,8,18,8,1 - Group-I metal, one of the property:low density
iii) Covalent means two non-metals..so select only non-metals from the table..(except A) B- 2,8,4 and F 2,8,18,18,7
try to bond A with both of them (by drawing the atomic structure)
It is not possible with B, so it has to be F
OR if you want to be sure of your answer draw the bonding between A and F, gives you AF3
iv)its B, always giant covalent structure of diamond has 4 electrons in the valence shell(outermost shell). Hence B
Revise Structure of diamond ;)
v) A
hey why nt C i mean it seem more stable den D
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@Nidzzz D has A FULL OUTER ELECTRON SHELL .
That means it is a GROUP 8 ELEMENT i.e. it is inert hence it is UNREACTIVE and VERY stable !!
C has only 2 electrons in its outer electron shell. That means it is in Group 2 and is an alkali earth metal like Magnesium. SO it is VERY REACTIVE !!!!
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hey why nt C i mean it seem more stable den D
Any element having completed their octet state (eight electrons in the outermost shell) is stable.
C has 2 electrons in the valence shell, so it tends to loose them fast, also it is very reactive
oh sorry Ari I'd already typed this :P
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Any element having completed their octet state (eight electrons in the outermost shell) is stable.
C has 2 electrons in the valence shell, so it tends to loose them fast, also it is very reactive
oh sorry Ari I'd already typed this :P
oh sorry Ari I'd already typed this !!!!! >:(
yyyaya i m dumb thanz i didny notice
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oh sorry Ari I'd already typed this !!!!! >:(
yyyaya i m dumb thanz i didny notice
I never intended to offend ya! ;)
You are not dumb!!
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oh sorry Ari I'd already typed this !!!!! >:(
yyyaya i m dumb thanz i didny notice
Nidzzz you asked us for help. We helped you, dont get your ego involved in this matter.
Frankly, its not my problem if you couldnt understand my concept. However, Vin and I took the time out to help you.
The least you could have done is thanked us.
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Nidzzz you asked us for help. We helped you, dont get your ego involved in this matter.
Frankly, its not my problem if you couldnt understand my concept. However, Vin and I took the time out to help you.
The least you could have done is thanked us.
ari i did suppose vin might be Knowin dat i was jokin in it n i did mention at de last i didnt c it MY mistake
THANKZ 4 ur help
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how does electrostatic dust precipitator removes charged particles from sulphur dioxide ??? ??? ??? ???
thanz
Long time lurker here.
An electrostatis dust percipitator works to remove smoke and another dust particles from gas exhaust from factories. It passes the exhaust through a mesh that is positivly/negatively charged, causing the dust particles to become "ditto" charged. The gas is then passed through a pipe with opposite charged walls.
As the dust is charged, and opposites attract, the dust is attracted to the walls.
As far as I remember, that's all we need to know.
(http://www.bbc.co.uk/schools/gcsebitesize/science/images/ph_elect28.gif)
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Okay, I'll start with i)
a)
i)D :2,8,18,8 - stable
ii)E :2,8,18,8,1 - Group-I metal, one of the property:low density
iii) Covalent means two non-metals..so select only non-metals from the table..(except A) B- 2,8,4 and F 2,8,18,18,7
try to bond A with both of them (by drawing the atomic structure)
It is not possible with B, so it has to be F
OR if you want to be sure of your answer draw the bonding between A and F, gives you AF3
iv)its B, always giant covalent structure of diamond has 4 electrons in the valence shell(outermost shell). Hence B
Revise Structure of diamond ;)
v) A
Oh thx a lot.. ;D
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Long time lurker here.
An electrostatis dust percipitator works to remove smoke and another dust particles from gas exhaust from factories. It passes the exhaust through a mesh that is positivly/negatively charged, causing the dust particles to become "ditto" charged. The gas is then passed through a pipe with opposite charged walls.
As the dust is charged, and opposites attract, the dust is attracted to the walls.
As far as I remember, that's all we need to know.
(http://www.bbc.co.uk/schools/gcsebitesize/science/images/ph_elect28.gif)
thanz alot Zephyrs
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y'all i need advice on the following:
what is the best way to study chem paper 3 ? ...............
i believe i should do some past paper and should mostly focus on memorizing the syllabus
plz anwer ASAP
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DO past papers THEN read your textbook.
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DO past papers THEN read your textbook.
ok thx :D
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HEy guys ,i'm really in trouble, the problem is that my chemistry guide(bob berry) is missing an important page(Pg 33 to 34) ,about excess reagents and coincidentally ,i always mess up that question and lose marks,so could someone scan the page off the guide and post it,or even a picture would do, i'm sure you''ll wil understand ,thanks! ;D :D ;) :)
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guys do u have any small notes for stoichiometry
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guys do u have any small notes for stoichiometry
See if this (https://studentforums.biz/index.php/topic,8536.0.html)topic has some ...
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When does ovulation occur in a female (like which day of the menstrual cycle)?
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When does ovulation occur in a female (like which day of the menstrual cycle)?
after 14 days
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_3.pdf
questio 5 (b)
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_3.pdf
questio 5 (b)
This has been answered before.
no problem.. ;)
anyways
the vol. of phosphate soln used in cm3 is half the height of the ppt in mm
also at 8cm3 all the soln is used up. tht is because adding more does not increase the height of the ppt meaning there was no further reaction on adding more.
also the formula is T3(PO4)2-----because
u take it as 12cm3 of T nitrate react with 8cm3 of sodium phosphate (thts wen all the reactants r used up)
so.....12:8...simplify it
12:8
6:4
3:2
and therefore u get T3(PO4)2
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Okay one silly question about the same, how does it matter if the "the vol. of phosphate soln used in cm3 is half the height of the ppt in mm"?
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Okay one silly question about the same, how does it matter if the "the vol. of phosphate soln used in cm3 is half the height of the ppt in mm"?
How do you mean by "half the height", the question didn't ask it, right?
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mohit1234 mentioned it... yea the question never asked about it... I know mentioning is not sinning but does it affect anything or is it important?
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mohit1234 mentioned it... yea the question never asked about it... I know mentioning is not sinning but does it affect anything or is it important?
Not important at all. In my view, as long as you say at 8cm3, maximum height of ppt was reached, then that's the first mark. I believe, writing that statement does not help or indeed actually answers the question, so no I don't think it's needed.
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Question: ???
When asked to to draw diagram of a compound that shows
formula of compound, charges on ions, arrangement of valency electrons around negative ions.
For example MgCl2 we just draw both, with arrows of the moving electrons to cl.
unlike covalent bonding.
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Question: ???
When asked to to draw diagram of a compound that shows
formula of compound, charges on ions, arrangement of valency electrons around negative ions.
For example MgCl2 we just draw both, with arrows of the moving electrons to cl.
unlike covalent bonding.
For only ionic bonding, just draw the outer shell and don't bother with electron transfer stuff.
So for the diagram below of calcium chloride, this is a very good diagram except you only need to draw the outer shell, and not all the shells. Sorry couldn't find a better diagram.
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Question: ???
When asked to to draw diagram of a compound that shows
formula of compound, charges on ions, arrangement of valency electrons around negative ions.
For example MgCl2 we just draw both, with arrows of the moving electrons to cl.
unlike covalent bonding.
Hmm, yeah i guess thts wht u have to do. :) draw arrows showing th direction of the moving electrons and then also showing like for eg: 2[Cl]^+ to show how the compound is finally. Umm hope u get me? :) lol ivo's got it.. :P
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does anyone have biology paper 1 november 2009 ??
cause its not openning on free exam papers or xtreme pastpapers either ..
if u have the pprs or any link please post them ..
thnk u :D
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does anyone have biology paper 1 november 2009 ??
cause its not openning on free exam papers or xtreme pastpapers either ..
if u have the pprs or any link please post them ..
thnk u :D
Please click here (https://studentforums.biz/index.php/topic,54.msg231725.html#msg231725).
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Please click here (https://studentforums.biz/index.php/topic,54.msg231725.html#msg231725).
Which varient with ms or without?
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Which varient with ms or without?
What do you mean? Both variants of qp and ms are there.
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Oh ok sorry tht was extremely wierd i dnt even know why i asked the question.
Soory again (:
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For only ionic bonding, just draw the outer shell and don't bother with electron transfer stuff.
So for the diagram below of calcium chloride, this is a very good diagram except you only need to draw the outer shell, and not all the shells. Sorry couldn't find a better diagram.
Ok i get it, ;D
Thanks Ivo and Raywin
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For only ionic bonding, just draw the outer shell and don't bother with electron transfer stuff.
So for the diagram below of calcium chloride, this is a very good diagram except you only need to draw the outer shell, and not all the shells. Sorry couldn't find a better diagram.
Oh! I was been taught only in covalent bonding we are supposed to draw the valence shell and full electronic configuration of an ionic bond, exactly like in the diag. that you have uploaded. :-\
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Oh! I was been taught only in covalent bonding we are supposed to draw the valence shell and full electronic configuration of an ionic bond, exactly like in the diag. that you have uploaded. :-\
Hmm, my teacher said that you don't, it's a waste of time and you won't get marks, apparantly.
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Hmm, my teacher said that you don't, it's a waste of time and you won't get marks, apparantly.
same goes for my teacher ;)
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Oh okay, thank you for the info.
-
quick question in june 2007 chemistry last line in the paper where it says number of double bonds and 7 c same paper iii in ms it says con oil i didnt find it in my book wat oil is it is there others?
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quick question in june 2007 chemistry last line in the paper where it says number of double bonds and 7 c same paper iii in ms it says con oil i didnt find it in my book wat oil is it is there others?
d) 884g of fat reacts with 8.84*86.2=762g of iodine.
One mole of fat reacts with 762/254=3 moles of iodine molecules.
Number of double bonds in one molecule of fat is 3.
c) iii) Simply look at the table for the one with the lowest saturated fat, which is corn oil.
Understood, qui ou non?
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i dnt get how u got the number of double bonds and can a strong acid displace a weaker acid from its salt solution or a stronger base displace weaker base from its salt solution By the way i dnt speak paris :p
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i dnt get how u got the number of double bonds and can a strong acid displace a weaker acid from its salt solution or a stronger base displace weaker base from its salt solution By the way i dnt speak paris :p
In the question it says: one mole of I2 reacts with one mole of "1 carbon-carbon double bond".
The answer you found was 3 moles of iodine molecules. So, 3 moles reacts with 3 moles of "1 carbon-carbon double bond", so that would make 3 double bonds.
For your second question, please give an example.
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Hey guys, :) umm a doubt. In electrolysis, is the products formed at the cathode and anode influenced by whether its a concentrated or dilute solution? Like if it is a dilute solution, will the H+ ions will have more chance of going to the cathode rather than a less reactive metal say copper and likewise the other way round, a concentrated solution will have the metal going to the cathode rather than Hydrogen? Does this happen? Thanks ;D
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Heey,
I have a question:
How do you know that a base is soluble or not?
And to make a soluble salt, when do you use titration and when do you use the method where you add excess of the base to the acid?
Thanks a lot in advance :)
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Hey guys, :) umm a doubt. In electrolysis, is the products formed at the cathode and anode influenced by whether its a concentrated or dilute solution? Like if it is a dilute solution, will the H+ ions will have more chance of going to the cathode rather than a less reactive metal say copper and likewise the other way round, a concentrated solution will have the metal going to the cathode rather than Hydrogen? Does this happen? Thanks ;D
yes, you are right...
have a look at this presentation
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Heey,
I have a question:
How do you know that a base is soluble or not?
And to make a soluble salt, when do you use titration and when do you use the method where you add excess of the base to the acid?
Thanks a lot in advance :)
All Chlorides, bromides and iodides are soluble except the chloride/bromide/iodide of lead, silver and mercury.
All carbonates are insoluble except Sodium, potassium and all group 1 metals and ammonium carbonates
All hydroxides are insoluble except Sodium, potassium(All group 1 metals in general), ammonium, calcium, strontium and barium hydroxides, aq.ammonium, which are soluble.
All sulfates are soluble except the sulfates lead , barium and calcium
If you want to make a soluble salt, you must use the bases in bold^^ and ofc. an acid
If you want the acid to be reacted fully then you may use excess of a base
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yes, you are right...
have a look at this presentation
Thanks a lott.. :)
-
guys i have a question....... the question says that the atomic structure of substance X is shown it has 2 electrons in the first and outer shell n in the nucleus 5 proton n 6 nucleons what's the relative charge n mass of each ???
-
Okay the nucleus has 5 protons and 6 nucleons
so originally the atom had 5 electrons too .. and now as there are only 4 electrons the net charge is +1 as thw element has lost one electron and there is a surplus of 1 proton in the nucleus
I don't know the diagram so I am guessing that there are two atoms shown..one is neutral and one has +1 charged, so the mass remains the same as electrons have negligible mass.
(mentioning the year would help me a lot in giving an accurate answer ) ;)
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In the question below :
Is it CONCENTRATED aqueous Rubidium Chloride ?
OR
Is it DILUTE aqueous Rubidium CHloride ?
As you know the products will differ in each case, so how do I determine which one it is ???
-
What does the mark scheme say?
-
What does the mark scheme say?
This is AN OLDDDDDD paper with a teacher MS that says Hydrogen and Chlorine are produced.
-
need help with s09 q5b...
-
need help with s09 q5b...
no problem.. ;)
anyways
the vol. of phosphate soln used in cm3 is half the height of the ppt in mm
also at 8cm3 all the soln is used up. tht is because adding more does not increase the height of the ppt meaning there was no further reaction on adding more.
also the formula is T3(PO4)2-----because
u take it as 12cm3 of T nitrate react with 8cm3 of sodium phosphate (thts wen all the reactants r used up)
so.....12:8...simplify it
12:8
6:4
3:2
and therefore u get T3(PO4)2
-
This is AN OLDDDDDD paper with a teacher MS that says Hydrogen and Chlorine are produced.
Ohkay.
I just went through my collins text
It says
In an aqueous solution...both positive ions will go to the cathose but only the H+ ion is discharged as H2
similarly both negative ions go to the anode but only the Cl- ion is discharged as Cl2
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So when they say just aqueous we assume its concentrated and hence OH- ions WILL NOT be discharged at the anode ?
Instead Cl- will discharge ?
-
That's what the book says :-\
If you find a similar question, it'll be easier to compare and check if they ALWAYS mean aqueous=conc
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That's what the book says :-\
If you find a similar question, it'll be easier to compare and check if they ALWAYS mean aqueous=conc
in 2009 there was a similar question but they were specific about it being CONCENTRATED aqueous.
Thanks Nid ;)
+rep
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Not a problem :)
-
ahhh i see thanks! :)
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Hey guys, another doubt, what are macromolecules? Are they the same as polymers?? ??? ??? ??? And also can acidified potassium manganate (vii) be decolourised by an alkene? Thanks once again.. :D :D
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Hey guys, another doubt, what are macromolecules? Are they the same as polymers?? ??? ??? ??? And also can acidified potassium manganate (vii) be decolourised by an alkene? Thanks once again.. :D :D
Macromolecules are substances with large molecular structure; like silicon, diamond, etc..
And yes, potassium permanganate is decolorized when added to an alkene. (purple-->colourless)
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Macromolecules are substances with large molecular structure; like silicon, diamond, etc..
And yes, potassium permanganate is decolorized when added to an alkene. (purple-->colourless)
Oh kay, so macromolecules have nothin to do with polymers?? and thank you.. ;D
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Oh kay, so macromolecules have nothin to do with polymers?? and thank you.. ;D
Macromolecules are defined as made up of many smaller units- monomers.
So polymers ARE macromolecules.
What AF told you is ANOTHER definition of macromolecue.
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Macromolecules are defined as made up of many smaller units- monomers.
So polymers ARE macromolecules.
What AF told you is ANOTHER definition of macromolecue.
Oh ryte, got it, thanks you Ari and AF.. :D :D ;D
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Not all macromolecules are polymers.
But all polymers are macromolecules
-
Not all macromolecules are polymers.
But all polymers are macromolecules
Couldn't have said it better myself. +rep ;)
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Thanks ari.
-
can any 1 tell me how to draw but-2-ene please
-
Has already been answered by mohit in the other thread u posted this.
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H H
| |
H-C-C = C- C-H
| | | |
H H H H
-
H H
| |
H-C-C = C- C-H
| | | |
H H H H
THANKS
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can any 1 tell me how to draw the structure of polypropane,polybutane
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can any 1 tell me how to draw the structure of polypropane,polybutane
u mean polypropene and polybutene?
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u mean polypropene and polybutene?
yes
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u mean polypropene and polybutene?
Here is polypropene.
-
Quick question.
Glusoce = simple sugar HO-l_l-OH
Starch = complex sugar -o-l_l-o-
-
Here is polypropene.
thanks i got it how to draw polybutene
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thanks i got it how to draw polybutene
I think it's this. Please can someone confirm this.
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how do you figure out the limiting reactant if the mole ratio is NOT 1:1 :-[
-
@ Ivo Spot on :)
-
Quick question.
Glusoce = simple sugar HO-l_l-OH
Starch = complex sugar -o-l_l-o-
Glucose - Monosaccharide
Starch - Polysaccharide
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Quick question.
Glucose = simple sugar HO-l_l-OH
Starch = complex sugar -o-l_l-o-
yes..
HO-l_l-OH = monosaccharide
OH-|_|-O-|_|-OH = disaccharide
-O-l_l-O- = polysaccharide
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how do you figure out the limiting reactant if the mole ratio is NOT 1:1 :-[
Example : Mg + 2HCl --> MgCl2 + H2
If 0.1 mol of Mg reacts with 0.1 mol of HCl, the limiting reactant is HCl acid because, i we look at the equation, for every mole of Mg used we need 2 moles of HCl.
So there will still be 0.1/2 0.05 mol of Mg left when the HCl is used up.
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can someone help me?
in june'08 chemistry p3 number 1.e
"name an element that has oxidation states of 2 and 3 only"
so, how do you find the answer for all questions like this one?
-
iron
-
Metal that have varying oxidation numbers are transition metal.
Fe-->2+/3+
Cu-->+/2+
etc...
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Questionnnn , why do some elements react with water to form oxides but some hydroxides? ???
-
As a general rule, if a metal reacts with cold water, you get the metal hydroxide. If it reacts with steam, the metal oxide is formed. This is because the metal hydroxides thermally decompose (split up on heating) to give the oxide and water.
Though, there are some who dont form oxides at all, only hydroxides
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If someone could please answer my doubt, that would be greatly appreciated.
For the 2 diagrams attached, do both represent poly(but-1-ene)?
-
Yup both are fine
-
definitley no
because
1 has 4 carbons
and 1 has 3
met 1
eth 2
prop 3
but 4
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YIKES!!!!
sry
didnt c the 2
yup
ur rite
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As a general rule, if a metal reacts with cold water, you get the metal hydroxide. If it reacts with steam, the metal oxide is formed. This is because the metal hydroxides thermally decompose (split up on heating) to give the oxide and water.
Though, there are some who dont form oxides at all, only hydroxides
so lets say they give you a question liek
Both metals react with water
i) Write a word equation for the reaction of zinc and water and state the reaction conditions
ii) Write an equation for the reaction of strontium with water and give the reaction condition.
:o
how do we know if it's gonna make oxides/hydroxides?
-
Both would form hydroxides in cold water.
Although Zinc would have a slower reaction since it's less reactive compared to Strontium.
-
wouldnt zinc be in steam???
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wouldnt zinc be in steam???
It would form oxide with steam
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wud this hav 2 do sumthin with the reactivity series???
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wud this hav 2 do sumthin with the reactivity series???
but obv :P
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but obv :P
eh? so whats the rule for this? :-\
-
but obv :P
yh
because i mean
im lost in that subject...
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Read through your textbook.
There's no rule as such. it's just based on reactivity. Some metals are simply more reactive than others.
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Read through your textbook.
There's no rule as such. it's just based on reactivity. Some metals are simply more reactive than others.
no not that way
it ws sumthin like
above 'this' metle
only elctrolysis
and so on so forth
cud u tell me bout that
like explain
plz?
-
no not that way
it ws sumthin like
above 'this' metle
only elctrolysis
and so on so forth
cud u tell me bout that
like explain
plz?
and for my question, i couldnt find it in my textbook. which is why i had to ask on sf? lol
-
whats your question? and could someone please explain how increasing pressure,temperature, and other stuff affects reactions in gases
-
sorry i have another question...
s09 q9c
If it has already been answered then can u please give me the link
-
whats your question? and could someone please explain how increasing pressure,temperature, and other stuff affects reactions in gases
its okay :) hehs got the answer already..
anyways.. your question.
increasing the pressure will shift the equilibrium to the side with less molecules
so for example A+B <-> C , increasing the pressure here will shift the equilibrium to the right & youll get a higher yield
decreasing the pressure will shift equilibrium to the side with more molecules
*only applies to gases
increasing the temperature will favour the forward reaction in an endothermic reaction
decreasing the temperature will favour the forward reaction in an exothermic reaction
increasing the concentration on the reactants side will shift equilibrium to the right & hence increasing yield
increased concentration on the products side will shift equilibrium to the left & hence the rate of backward reaction will be greater than the forward reaction.
hope it helps? :b lol.
-
Can anyone answer this?
"Draw a labelled diagram to show how could u condense and collect the water vapour produced when a hydrated salt is heated".
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its okay :) hehs got the answer already..
anyways.. your question.
increasing the pressure will shift the equilibrium to the side with less molecules
so for example A+B <-> C , increasing the pressure here will shift the equilibrium to the right & youll get a higher yield
decreasing the pressure will shift equilibrium to the side with more molecules
*only applies to gases
increasing the temperature will favour the forward reaction in an endothermic reaction
decreasing the temperature will favour the forward reaction in an exothermic reaction
increasing the concentration on the reactants side will shift equilibrium to the right & hence increasing yield
increased concentration on the products side will shift equilibrium to the left & hence the rate of backward reaction will be greater than the forward reaction.
hope it helps? :b lol.
umm... i already know this ,see i was kinda wondering why this happens... sorry
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umm... i already know this ,see i was kinda wondering why this happens... sorry
ohhhh Lollll okay :) SRRYY.
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Can anyone answer this?
"Draw a labelled diagram to show how could u condense and collect the water vapour produced when a hydrated salt is heated".
hope this is wht u need
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radioactivity is not in our portion right?? (cant be bothered checkin the syllabus)
its ther in the previous papers but not in ny of the recent papers!!
-
hope this is wht u need
or maybe this.... idk if its correct
-
m/j 2005
chem ppr 3
q4 d
how do u noe x=2
Thanks
-
umm... i already know this ,see i was kinda wondering why this happens... sorry
I think i can explain y but on one condition my doubt gets answered about da labelled diagram, ok?
U know dat any reversible reaction at da state of equilibrium means dat neither sides is prevailing so if it goes in one direction, it undergoes da reverse reaction so it continues to go like this until u change da conditions which could be increasing da pressure as da first example, so think of a piston being pushed, what happens to volume of air, it decreases, rite? so this is da exact same thing on increasing pressure, volume decreases so da side of da rection with lower volume (remember this only for gas) would be favoured, u can know that by looking at da no. of moles...
NOW, da second example is increasing da concentration, if u add more of A in this reaction, wat would happen? A+B=>C+D
There is more of A nd this disturbs da equilibrium in order to return to it, the reaction speeds up towards the RHS in order to remove da extra A added
LAST is temperature, usually either da forward or da backward would be exothermic(gives off heat) nd naturally da other would be endo (takes in heat)
so when u raise da temp., equilibrium is again disturbed so to decrease it da endo is favoured why because it takes in heat so will eventually lower da temp. Got it???
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MJ04 Q4 how do i know what salt to use, what cant it be a zinc oxide or hydroxide for preparing an insolubles salt?
-
no not that way
it ws sumthin like
above 'this' metle
only elctrolysis
and so on so forth
cud u tell me bout that
like explain
plz?
Method of Extraction
The method used depends on the reactivity of the metal
Very reactive metals
Electrolysis (Decomposing metal compound with electricity)
Potassium
Sodium
Calcium
Magnesium
Aluminium
Moderately reactive metals
Heating metal oxide with coke
Zinc
Iron
Lead
Low Reactivity metals
Heating metal compounds in air
Copper
Silver
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m/j 2005
chem ppr 3
q4 d
how do u noe x=2
Thanks
looking it up
-
hope this is wht u need
Thanks
-
or maybe this.... idk if its correct
Thanks
-
looking it up
ok...umm...well... OK!...
79.1g of CaSO4 is 79.1/136 moles of CaSO4 (i.e. 0.58 moles)
20.9g of H2O is 20.9/18 moles water (ie. 1.16 moles)
now divide by the simplest mole ratio (0.58) to obtain X
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m/j 2005
chem ppr 3
q4 d
how do u noe x=2
Thanks
mol=mass/MM so for CaSO4 : mol=79.1/136 = 0.58mol and for H2O: mol=20.9/18= 1.16mol
To find x you have to find the mole ratio
so divide each of them with the smallest one
therefore in this case 0.58mol is smaller than 1.16 so 0.58/0.58=1 and x= 1.16/0.58=2 therefore x=2
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ok...umm...well... OK!...
79.1g of CaSO4 is 79.1/136 moles of CaSO4 (i.e. 0.58 moles)
20.9g of H2O is 20.9/18 moles water (ie. 1.16 moles)
now divide by the simplest mole ratio (0.58) to obtain X
oops didnt see you already replied :P
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sorry i have another question...
s09 q9c
If it has already been answered then can u please give me the link
can anyone pls ans my question... :'(
-
MJ04 Q4 how do i know what salt to use, what cant it be a zinc oxide or hydroxide for preparing an insolubles salt?
I'D LIKE A REPLY! theres been like 3 replies AFTER my post ,but no rresonse to my post! ???
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MJ04 Q4 how do i know what salt to use, what cant it be a zinc oxide or hydroxide for preparing an insolubles salt?
i dont know that one but i think sodium oxide or hydroxide would destroy the carbonate or something although carbonates are alkaline
-
thnxu both
:)
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can anyone pls ans my question... :'(
working....
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ok its like this Si + 2F2.... 7.2 grams= 7.2/38...(not 19 as it is the gas molecule not the atom)
so it becomes 0.189.... now since Si needs 2 moles of F2 0.08 moles needs 0.16 moles but F2 has 0.189 and therefore Si is the limiting agent
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can anyone pls ans my question... :'(
Ok calculate da no. of moles of Br2= 25 divided (80*2)= 0.156
then takin da ration Si: Br2 is 1:2 so if silicon is 0.07 then Br2 should be double it that is 0.14
but the real amount is 0.156 which is greater than 0.07 so bromine is in excess nd Silicon is da limiting reagent
Hope I helped
My answer is for da first variant
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MJ04 Q4 how do i know what salt to use, what cant it be a zinc oxide or hydroxide for preparing an insolubles salt?
I'D LIKE A REPLY! theres been like 3 replies AFTER my post ,but no rresonse to my post! ???
precipitation method uses two solubles to form an insoluble base
hydroxides are insoluble (except those of ammonia, barium and alkali metal (group 1) cations) so we cant use that
all oxides are also insoluble (except those of calcium, barium and alkali metal cations) so we cant use these either
we have to choose a soluble base. we can use chlorides as they are soluble. therefore zinc chloride+ sodium carbonate= zinc carbonate+ sodium chloride
Im not quite sure of my answer though. can some1 pls confirm
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thnku both for the answer!
i actually got the right answer but i was looking at the markscheme for a different variant! silly me! ;D
anyway Thanks guys!
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precipitation method uses two solubles to form an insoluble base
hydroxides are insoluble (except those of ammonia, barium and alkali metal (group 1) cations) so we cant use that
all oxides are also insoluble (except those of calcium, barium and alkali metal cations) so we cant use these either
we have to choose a soluble base. we can use chlorides as they are soluble. therefore zinc chloride+ sodium carbonate= zinc carbonate+ sodium chloride
Im not quite sure of my answer though. can some1 pls confirm
yeah its correct... although you could use sulphate or nitrate... both are soluble
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Umm...could someone tell me WHY increasing pressure favors the RHS of equation in gases... why it moves equilibrium to right
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Umm...could someone tell me WHY increasing pressure favors the RHS of equation in gases... why it moves equilibrium to right
An increase in pressure, decreases the volume for the forward reaction. Thus, the chances of an effective collision of the particles are more since the volume decreases. So, since the chances of the collisions in the forward reaction is more, it favors the RHS of the equation, this moves the equilibrium to the right. :) hope you got me. :D
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Increasing pressure favours the side which has fewer gas molecules or moles ,as a result the right hand sides will produce more gas mols,=higher yield!
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I haveee justtt one question :D..there is this question about using Calcium carbonate instead of calcium oxide .. I know that calcium carbonate is not soluble so it remains longer in soil.. but they say in MS .. that calcium carbonate the Ph cant go above 7 , but with calcium oxide it can go.. i dont get that part.. thanks in advance!
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u answered you own question!!
due to its property to noe dissolve in excess watering,rain, caco3 will not make the soil alkaline,on the other hand Cao is soluble to some extent and willl make the soil alkaline in PH
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Umm...could someone tell me WHY increasing pressure favors the RHS of equation in gases... why it moves equilibrium to right
okay, image the pivot and scale as in physics.. reaction of N2 + H2 as an example..
____ _____
| N2| | |
|H2 | |NH3|
------ | |
-------------------------------
|
Always when a reversible reaction is in equilibrium and you make a change(inc/dec. pressure/temp), it will do what it can to oppose the change.
Temp::Increase the temp. the heat will be used to both for forward as well as the backward reaction. Forward: N2 and H2 combine, backward:heat used to break NH3 to form. This is a state of dynamic equilibrium.
Pressure::Increase the pressure(by adding more N2 and H2), the mixture will act to oppose the change and eliminates these molecules by combining them to form NH3 so the equi. shifts to the right..
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u answered you own question!!
due to its property to noe dissolve in excess watering,rain, caco3 will not make the soil alkaline,on the other hand Cao is soluble to some extent and willl make the soil alkaline in PH
but hmm... How does it neutralize the acidity of the soil without increasing its Ph >_< ?
I got what you mean but im a bit confused
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but hmm... How does it neutralize the acidity of the soil without increasing its Ph >_< ?
I got what you mean but im a bit confused
You mean when you add either of them .. they react with the acidic parts or w.e and then just stop reacting unless they disolve ..? and when they disolve they would obviously make it Ph>7 ?
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I haveee justtt one question :D..there is this question about using Calcium carbonate instead of calcium oxide .. I know that calcium carbonate is not soluble so it remains longer in soil.. but they say in MS .. that calcium carbonate the Ph cant go above 7 , but with calcium oxide it can go.. i dont get that part.. thanks in advance!
Carbonate is a salt...so it's pH is neutral
whereas oxide of group 2 metals are alkaline.
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Could someone scan their guide,or click a pic or anything,but post it up here,this is about chemistry excess reagents, could you scan the part in bob berry's guides and put it up here Pg 33 -34 i thnk as you can see many people are having doubts bout the reagent stuff!! so this time around someone DO STH!! the last i got NO RESPONSE!,it will benefit lots of people
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but hmm... How does it neutralize the acidity of the soil without increasing its Ph >_< ?
I got what you mean but im a bit confused
CaCO3 insoluble in water, no change in pH. Hence pH remains 7
CaO, partially soluble in water, forms Ca(OH)2- a base, so the pH can go above 7 get it?
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Carbonate is a salt...so it's pH is neutral
whereas oxide of group 2 metals are alkaline.
Righttt >_<.. thanks vmuch
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If you answer questions like using the AS syllabus
for example they ask you why Ammonia is liquid while Nitrogen is gas ..
Cant you say the intermolecular forces in ammonia are hydrogen bonds while nitrogen is VDW?
They said in MS Ammonia has a higher boiling point .. thats true also XD
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Questionnn! ;D
Explain why metals are often used in the form of alloys?
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The main reason is since the alloy may (but not always) be stronger.
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Questionnn! ;D
Explain why metals are often used in the form of alloys?
Iron to stainless steel> does not rust
Alloys are stronger/harder
Can be used in specific proportion to create 'customised' properties :: Alloy of Al(Zn+Mg+cu)-Light weight and strong
Alloy-solder-to lower melting pt.
Brass-easy to shape
Cupro-nickel-Usually cheaper than silver(used as coins)
any more would be appreciated..
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@Vin we don't specifically need to know all the characteristics for alloys.
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@Vin we don't specifically need to know all the characteristics for alloys.
Yes, absolutely. But our teacher made us learn us all so I know most of them. ;D
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How do you show the charges in a diagram showing electronic configuration? I am kind of confused about how to show it ???
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(http://www.revisionworld.com/files/ionic%20bonding.jpg)
^^second diagram
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How do you show the charges in a diagram showing electronic configuration? I am kind of confused about how to show it ???
LOOK
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Hey guys. :) a small doubt, if asked to draw an ionic bonding diagram between any non-metal and metal wht exactly do we draw? ??? ??? ??? OH i was just solved... by ari.. :P
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Thanks vin. +rep.
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Thanks Vin and Ari :D
-
@Raywin
Look above your post.
-
LOOK
Hmm, I don't think you can just add 2- in the chloride ion. You need to copy the chloride ion twice, and put 1- each time I think.
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Hmm, I don't think you can just add 2- in the chloride ion. You need to copy the chloride ion twice, and put 1- each time I think.
It just struck me too. I'll edit it. Thanks for pointing it out.
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You can add "2" in front of the chloride ion, and put a "-" above it. That would do too.
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@Raywin
Look above your post.
Yep, saw tht aft i posted my comment.. :P Thx a lot, By the way.. :D
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i have this doubt in november 2007 5 iii can a strong base replace a weaker one from itz salt solution and another doubt in 2009 may 8 iii in the mark scheme it said NOT SODIUM ,LEAD OR ANY THING BELOW MAGNESIUM how come i dnt get it
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EVERYBODY +REP NID! SHE IS THE ONE WHO STARTED THIS THREAD! PLUS HE WAS THE ONE HELPING THE MOST!
SHE HELPED ALL OF US IN BIO & CHEMISTRY, ALL BOARDS AND ALL LEVELS!
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need help here! :S :(
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check the attachment
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phew! Thanks! :D
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EVERYBODY +REP NID! SHE IS THE ONE WHO STARTED THIS THREAD! PLUS HE WAS THE ONE HELPING THE MOST!
SHE HELPED ALL OF US IN BIO & CHEMISTRY, ALL BOARDS AND ALL LEVELS!
lol...Why all this? <3
God Bless you A.F <3 :)
Just pray for all of us giving our exams here...that's more than enough :)
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i have this doubt in november 2007 5 iii can a strong base replace a weaker one from itz salt solution and another doubt in 2009 may 8 iii in the mark scheme it said NOT SODIUM ,LEAD OR ANY THING BELOW MAGNESIUM how come i dnt get it
Sorry, I didn't get your first question. The question (b) is not about it, right? Can you give an example? :-[
About the second. The reason behind choosing any metal below Mg is that Sodium and Lead (also metals abv. Mg) don't react with alkenes. The acrylic acid contains a double bond (is unsaturated).
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VIIIIN U got Member of the month ;D
omg i was sure u would get it :D
and yes, Nid deserves it :D
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Such a big thing! Yes she deserves it totally..*ahem a typo :P*
Thanks Baladya.. ;D
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This is a probably a really dumb doubt but I'd appreciate if someone could please kindly answer it.
I'd just like to know in an electrochemical cell, when the more reactive metal loses the electrons and becomes a positive ion, I just wonder why here it becomes the negative cathode. And the less reactive metal gains the electrons becomes the positive anode?
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thx vin so anything above mg doesnt react wiz double bonds like alkenes but can u explain reason for that plz and for other question i meant q 5 c iii nov 07 just one more last thing can anyone upload a guide for finding limiting reagent from equation :D
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can any 1 exactli show hw u do we this question
Draw a diagram to show the arrangement of the valency electrons in one molecule
of the covalent compound hydrogen sulphide.
Use o to represent an electron from a sulphur atom.
Use x to represent an electron from a hydrogen atom
:-\
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This is a probably a really dumb doubt but I'd appreciate if someone could please kindly answer it.
I'd just like to know in an electrochemical cell, when the more reactive metal loses the electrons and becomes a positive ion, I just wonder why here it becomes the negative cathode. And the less reactive metal gains the electrons becomes the positive anode?
I think this has to do with electricity: From negative to postitive....
not sure tho
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This is a probably a really dumb doubt but I'd appreciate if someone could please kindly answer it.
I'd just like to know in an electrochemical cell, when the more reactive metal loses the electrons and becomes a positive ion, I just wonder why here it becomes the negative cathode. And the less reactive metal gains the electrons becomes the positive anode?
Well, as the more reactive metal gives e-, it is a source of -ve charge hence it is called the negative pole.. You see it isn't really the "cathode", its just
the -ve terminal of the battery.. same goes for the +ve terminal and not "anode".
The diag. unnecessary I guess...
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Well, as the more reactive metal gives e-, it is a source of -ve charge hence it is called the negative pole.. You see it isn't really the "cathode", its just
the -ve terminal of the battery.. same goes for the +ve terminal and not "anode".
The diag. unnecessary I guess...
Nah, good diagram and explanation! Thanks!!! ;D Just another thing, so electrons flow from the negative pole to the positive pole through the external circuit in wires, whereas ions move through the electrolyte?
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thx vin so anything above mg doesnt react wiz double bonds like alkenes but can u explain reason for that plz and for other question i meant q 5 c iii nov 07 just one more last thing can anyone upload a guide for finding limiting reagent from equation :D
I am really sorry, I don't really know the 'accurate' info. about it, also I don't think we have to know about it. So if a question like this turns up, stick to the other options like carbonates, oxides etc.
Ah, yes a strong base can effectively displace the weak salt. Simpler eg. 2NaOH + CuSO4 ---> Na2SO4 + Cu(OH)2
My apologies again 7ooD I don;t have any guide based on limiting reagent :-[ :'(
Also google "how to find limiting reagent", you'll get many links..
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Nah, good diagram and explanation! Thanks!!! ;D Just another thing, so electrons flow from the negative pole to the positive pole through the external circuit in wires, whereas ions move through the electrolyte?
yes
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can any 1 exactli show hw u do we this question
Draw a diagram to show the arrangement of the valency electrons in one molecule
of the covalent compound hydrogen sulphide.
Use o to represent an electron from a sulphur atom.
Use x to represent an electron from a hydrogen atom
:-\
Hydrogen Sulfide = H2S
H - 1
S - 2, 8, 6
would be something like..
oo
o o
H S H
x x
oo
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can some1 pls explain why theres no reaction when potassium hydroxide decomposes :-\
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thx vin so anything above mg doesnt react wiz double bonds like alkenes but can u explain reason for that plz and for other question i meant q 5 c iii nov 07 just one more last thing can anyone upload a guide for finding limiting reagent from equation :D
Have a look at this!
http://wiki.answers.com/Q/How_do_you_solve_limiting_reagent_problems
^^ a lot but read the starting part..
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somebody pls explain to me this...
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can some1 pls explain why theres no reaction when potassium hydroxide decomposes :-\
Sodium carbonate and Potassium carbonate, even when heated to a high temperature, do not decompose.
Sulphites of sodium and potassium do not decompose when heated.
Lowest oxides of metals (K2O, MgO, Al2O3) do not decompose when heated:: Exceptions Mercury and silver oxides decompose when heated, ZnO- yellow when hot, white when cool.
Don't ask why because they are not supposed to decompose WHEN HEATED.. ;)
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no problem.. ;)
anyways
the vol. of phosphate soln used in cm3 is half the height of the ppt in mm
also at 8cm3 all the soln is used up. tht is because adding more does not increase the height of the ppt meaning there was no further reaction on adding more.
also the formula is T3(PO4)2-----because
u take it as 12cm3 of T nitrate react with 8cm3 of sodium phosphate (thts wen all the reactants r used up)
so.....12:8...simplify it
12:8
6:4
3:2
and therefore u get T3(PO4)2
this answers ur question catalyst
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Sodium carbonate and Potassium carbonate, even when heated to a high temperature, do not decompose.
Sulphites of sodium and potassium do not decompose when heated.
Lowest oxides of metals (K2O, MgO, Al2O3) do not decompose when heated:: Exceptions Mercury and silver oxides decompose when heated, ZnO- yellow when hot, white when cool.
Don't ask why because they are not supposed to decompose WHEN HEATED.. ;)
k Thanks ill try to keep this in mind ;)
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k Thanks ill try to keep this in mind ;)
There are more I guess.. I can't recollect them. Unfortunately nothing in the book :-\
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There are more I guess.. I can't recollect them. Unfortunately nothing in the book :-\
what about nitrite?
nd sulphite and carbntes of ONLY NA and K do not decompose?
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what about nitrite?
nd sulphite and carbntes of ONLY NA and K do not decompose?
Nitrates of Na and K decompose, but in a different way.. products are different
2 Zn(NO3)2 ----> 2ZnO + 4 NO2 + O2
2 KNO3 ----> 2 KNO2 + O2
Hg(NO3)2 ----> 2Hg + 2NO2 + O2
2AgNO3 ----> 2Ag + 2 NO2 + O2
Yup only Na and K
okay, not sure about nitrites, because they are formed by the decomposition of (K, Na)nitrates itself..
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this answers ur question catalyst
thx girl... :D
also mohit man...
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hey...
Could someone plzz answer question 5 b from chemistry 2009 may june variant one....
-
hey...
Could someone plzz answer question 5 b from chemistry 2009 may june variant one....
here you go
https://studentforums.biz/index.php/topic,1411.msg249826.html#msg249826
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HEATING HYDROXIDES
Sodium hydroxide and potassium hydroxide are NOT CHANGED by heating
them.
Calcium hydroxide and magnesium hydroxide behave in the same way.
HYDROXIDE + HEAT = OXIDE + WATER
Ca(OH)2(aq) = CaO(s) + H2O(l)
Mg(OH)2(aq) = MgO(s) + H2O(l)
Iron (III) hydroxide is also decomposed by heating to form iron (III) oxide and
water.
2Fe(OH)3(s) = Fe2O3(s) + 3H2O(l)
HEATING NITRATES
Group 1 nitrate + heat = group 1 nitrite + oxygen gas
2NaNO3(s) = 2NaNO2 + O2(g)
2KNO3(s) = 2NKNO2 + O2(g)
All other nitrates behave in the same way when heated
NITRATE + HEAT = OXIDE + NITRITE + OXYGEN GAS
2Ca(NO3)2 = 2CaO(S) + 4NO2(g) + O2(g)
2Cu(NO3)2 = 2CuO(S) + 4NO2(g) + O2(g)
2Zn(NO3)2 = 2ZnO(S) + 4NO2(g) + O2(g)
-
Hydrogen Sulfide = H2S
H - 1
S - 2, 8, 6
would be something like..
oo
o o
H S H
x x
oo
thanz pal :)
-
HEATING HYDROXIDES
Sodium hydroxide and potassium hydroxide are NOT CHANGED by heating
them.
Calcium hydroxide and magnesium hydroxide behave in the same way.
HYDROXIDE + HEAT = OXIDE + WATER
Ca(OH)2(aq) = CaO(s) + H2O(l)
Mg(OH)2(aq) = MgO(s) + H2O(l)
Iron (III) hydroxide is also decomposed by heating to form iron (III) oxide and
water.
2Fe(OH)3(s) = Fe2O3(s) + 3H2O(l)
HEATING NITRATES
Group 1 nitrate + heat = group 1 nitrite + oxygen gas
2NaNO3(s) = 2NaNO2 + O2(g)
2KNO3(s) = 2NKNO2 + O2(g)
All other nitrates behave in the same way when heated
NITRATE + HEAT = OXIDE + NITRITE + OXYGEN GAS
2Ca(NO3)2 = 2CaO(S) + 4NO2(g) + O2(g)
2Cu(NO3)2 = 2CuO(S) + 4NO2(g) + O2(g)
2Zn(NO3)2 = 2ZnO(S) + 4NO2(g) + O2(g)
NITRATE + HEAT = OXIDE + NITROGEN DIOXIDE + OXYGEN GAS
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Nitrates of Na and K decompose, but in a different way.. products are different
2 Zn(NO3)2 ----> 2ZnO + 4 NO2 + O2
2 KNO3 ----> 2 KNO2 + O2
Hg(NO3)2 ----> 2Ag + 2NO2 + O2
2AgNO3 ----> 2Ag + 2 NO2 + O2
Yup only Na and K
okay, not sure about nitrites, because they are formed by the decomposition of (K, Na)nitrates itself..
Hey Vin,
Hg(NO3)2 ----> 2Ag + 2NO2 + O2 Where did the Ag come from? ??? lol isnt it supposed to be Hg? :P
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Hey Vin,
Hg(NO3)2 ----> 2Ag + 2NO2 + O2 Where did the Ag come from? ??? lol isnt it supposed to be Hg? :P
Oh sorry dude. I was in a hurry... :-[
-
Oh sorry dude. I was in a hurry... :-[
Hahaha, np. :D
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Guys, in polymers, whts a Single repeating unit? ??? Thanks a lot.. :D
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Guys, in polymers, whts a Single repeating unit? ??? Thanks a lot.. :D
"monomer "
they repeat to form a long chaine macromelecule ( polymer )
-
"monomer "
they repeat to form a long chaine macromelecule ( polymer )
But doesn't that happen in any other polymer? ??? Thanks :)
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But doesn't that happen in any other polymer? ??? Thanks :)
monomers are in all polymers < everything has a different monomer
poly ( ETHEENE ) has ethene monomer
poly ( propene ) has propmene monemer
ethene and propene are the repeating units
in the case CONDESATION polymerisation
there is a repeating unit for nylon ( DIAMINE+ DICARBOXILYIC ACID )
there is a repeating unit for terylene ( DIOL + DICARBOXYILC ACID )
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monomers are in all polymers < everything has a different monomer
poly ( ETHEENE ) has ethene monomer
poly ( propene ) has propmene monemer
ethene and propene are the repeating units
in the case CONDESATION polymerisation
there is a repeating unit for nylon ( DIAMINE+ DICARBOXILYIC ACID )
there is a repeating unit for terylene ( DIOL + DICARBOXYILC ACID )
Oh, so repeating units are just monomers? Ryte :) Thanks a lot once again.. ;D
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Oh, so repeating units are just monomers? Ryte :) Thanks a lot once again.. ;D
for polyethene only 1 type of monemer
for nylon , 2 types of monomers , diamine and dicarboxylic acid (so i prefer to call this the repeating unit of nylon )
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for polyethene only 1 type of monemer
for nylon , 2 types of monomers , diamine and dicarboxylic acid (so i prefer to call this the repeating unit of nylon )
Oh k, thanks, :)
-
hi?
-
help anyone
What volume of carbon dioxide is produced by burning 90 g of ethane in air?
-
Guys, can someone explain the content of section 6.2 in the chemistry syllabus? bcuz i rlly dont get anything from it o.o' , Thank You =]
-
is it 144 dm3?
-
is it 144 dm3?
but hw
-
help anyone
What volume of carbon dioxide is produced by burning 90 g of ethane in air?
C2H6 + 3.5O2 --------> 2CO2 + 3H2O
After you form the above equation do this:
90g / (24+6) = 3 moles of ethane
2*3 moles = 6 moles of CO2 (using the molar ratio)
6*24 = 144 dm3
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u forgot to balance the O2 in the equation , but u didnt nned it anyway
and yeah thats how u do it NIdzz ^
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u forgot to balance the O2 in the equation , but u didnt nned it anyway
and yeah thats how u do it NIdzz ^
I balanced it correctly on the rough paper I had; I was in a rush so I missed it out whilst typing :-[
I removed the quote from your post so Nidzzz doesnt get confused, is that alright ?
-
yea sure np
good luck 2mrw !
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good luck....pray for me too.... i'm a disaster... i finished the lost symbol yesterday...lol
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I got 2 questions if someone knows atleast one im glad to have the answer. Ok so extracting aluminium, after the aluminium froms and O2 forms up it reacts with the carbon electrodes so they need to be replaced, but what confuses me is why are the electrodes made of carbon in the first place? why not something which wouldnot react with the oxygen? ???
and the second question is not really a question but im confused, what are the carbon chain lengths of the oil fractions seperated by fractional distillation, each one has a different carbon chain length but I got 2 text books and the teachers notes and they all give different carbon chains, so which one should I study for the IGs? ???
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yea sure np
good luck 2mrw !
Thanks. Good Luck to you to ;)
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@mdwael The electrodes used have to be unreactive right ? Now remember this is an industrial process, you cant use platinum because its too expensive and many other metals would melt at 900 deg c.
So carbon is cheap and a good conductor.
You dont need to memorise the carbon chains for the exam - just the names of the fractions and their uses.
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I got 2 questions if someone knows atleast one im glad to have the answer. Ok so extracting aluminium, after the aluminium froms and O2 forms up it reacts with the carbon electrodes so they need to be replaced, but what confuses me is why are the electrodes made of carbon in the first place? why not something which wouldnot react with the oxygen? ???
and the second question is not really a question but im confused, what are the carbon chain lengths of the oil fractions seperated by fractional distillation, each one has a different carbon chain length but I got 2 text books and the teachers notes and they all give different carbon chains, so which one should I study for the IGs? ???
because then aluminium might react with it or the oxygen might... or the electrode might melt...i guess
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You dont need to memorise the carbon chains for the exam - just the names of the fractions and their uses.
what are the fractions....i keep forgetting the names... lemme see... gases,petrol,paraffin,diesel,lubricating oil and bitumen..... this is the correct order right?
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@mdwael The electrodes used have to be unreactive right ? Now remember this is an industrial process, you cant use platinum because its too expensive and many other metals would melt at 900 deg c.
So carbon is cheap and a good conductor.
You dont need to memorise the carbon chains for the exam - just the names of the fractions and their uses.
Thank you Ive been trying to memorize them
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what are the fractions....i keep forgetting the names... lemme see... gases,petrol,paraffin,diesel,lubricating oil and bitumen..... this is the correct order right?
refinery gas
gasoline (petrol )
naphthaline
paraffin/kerossene
dieself oils
fuel oil
lubrication oils
bitumen
-
all those fractions!!!!!!!!!!!!!
-
Yup check this it's from the syllabus, (what you have to know)
;)
-
all those fractions!!!!!!!!!!!!!
and their uses
-
AAAAAAAAAAAAAAAARRRRRRRRGGGGGGGGH!!!!!!!!!1
-
do we have 2 learn de no. of carbon atom present in each fraction
-
I think there is a poem or rhyme which makes it easier to memories them
so if anyone knows it.. :D
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do we have 2 learn de no. of carbon atom present in each fraction
I dont think so :-\, never learned that, and never seen it in my book,
confirm anyone
-
do we have 2 learn de no. of carbon atom present in each fraction
Nope, just them fractions and their uses.
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Guys, one doubt, is protein a condensation polymer? ???
-
Guys, one doubt, is protein a condensation polymer? ???
yes!
because water is formed also
remmebr addition polymer jsut form a polymer
condesnation forms a polymebr and a small molecule , which is usually water
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yes!
because water is formed also
remmebr addition polymer jsut form a polymer
condesnation forms a polymebr and a small molecule , which is usually water
Thanks :) and sometimes a question asks us to differentiate between additional polymers and condensation polymers, so how do we do tht? I noe one is condensation polymers give out water, and theres something abt the monomers ryte? ???
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Thanks :) and sometimes a question asks us to differentiate between additional polymers and condensation polymers, so how do we do tht? I noe one is condensation polymers give out water, and theres something abt the monomers ryte? ???
the first reason i gave above
the second reason :
monomers of addition polymers can only have a DOUBLE BOUND >c=c<
monomers of condesation polyemers can be made of 2 differnet monomers and can have >c=c< sometimes
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I dont think so :-\, never learned that, and never seen it in my book,
confirm anyone
Wait, im sorry, Helium and Nizzz ----> u need to know that as you go down the fractions, (i) the no. of carbon atoms increases, (ii)) it gets less flammable and (iii) its boiling point and melting point increases.
-
the first reason i gave above
the second reason :
monomers of addition polymers can only have a DOUBLE BOUND >c=c<
monomers of condesation polyemers can be made of 2 differnet monomers and can have >c=c< sometimes
Ryte, thanks a lot :)
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Is this how you draw starch?
-(-O--[ ] --)n-
Thanks
-
Is this how you draw starch?
-(-O--[ ] --)n-
Thanks
yep glucose , starch and cellulose! ( carbohydrates )
-
Is this how you draw starch?
-(-O--[ ] --)n-
Thanks
-(-O--[]--O--[]--O-)n-
I learnt it like this. :)
-
-(-O--[]--O--[]--O-)n-
I learnt it like this. :)
^^ ditto.. https://studentforums.biz/index.php/topic,8790.msg254640.html#msg254640
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Wait, im sorry, Helium and Nizzz ----> u need to know that as you go down the fractions, (i) the no. of carbon atoms increases, (ii)) it gets less flammable and (iii) its boiling point and melting point increases.
Oh yes thank you, i know that,
i thought like the X number of carbon in it ;D
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Ryte guys, just confirming here,
In hydrolysis, all we need to know is that fats and oils can be hydrolyzed into glycerol and fatty acids using dilute acids (acid hydrolysis) and they can be hydrolyzed into glycerol and the salt of the acid by using an alkali (alkaline hydrolysis or saponification), and the salts of the higher fatty acids are called soaps.
Umm, this is all we need to know abt hydrolysis, right? ???
Thanks a lot guyss.. :D
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Wait, im sorry, Helium and Nizzz ----> u need to know that as you go down the fractions, (i) the no. of carbon atoms increases, (ii)) it gets less flammable and (iii) its boiling point and melting point increases.
thanks alot raywin but i was askin lke do we need 2 noe de no. of carbon in pertroleum , etcc
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thanks alot raywin but i was askin lke do we need 2 noe de no. of carbon in pertroleum , etcc
No, u do not need to know tht. :)
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Ryte guys, just confirming here,
In hydrolysis, all we need to know is that fats and oils can be hydrolyzed into glycerol and fatty acids using dilute acids (acid hydrolysis) and they can be hydrolyzed into glycerol and the salt of the acid by using an alkali (alkaline hydrolysis or saponification), and the salts of the higher fatty acids are called soaps.
Umm, this is all we need to know abt hydrolysis, right? ???
Thanks a lot guyss.. :D
u got it the wrong way..
sopnification ( alkaline hydrolysis ) of the fats will give you A sodium salt of carboxylic acid ( soap ) , and glycerol
then if u want the Carboxyic acid from the Na salt, you do acid hydrolsis
hydrolysis is heating under reflux with either acid / alkali
-
C2H6 + 3.5O2 --------> 2CO2 + 3H2O
After you form the above equation do this:
90g / (24+6) = 3 moles of ethane
2*3 moles = 6 moles of CO2 (using the molar ratio)
6*24 = 144 dm3
thanz a lot ari By the way ethene is gas y nt use this volume/ 24dm3
okko may be dey say its grams rght
thanz anyways
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thanz a lot ari By the way ethene is gas y nt use this volume/ 24dm3
okko may be dey say its grams rght
thanz anyways
WHen they say grams just assume it is a solid. FORGET EVERYTHiNG ELSE :P
No problem, always around to help ;)
-
also u have to know acid hyrolysis of proteins and starch ( carbs )
-
u got it the wrong way..
sopnification ( alkaline hydrolysis ) of the fats will give you A sodium salt of carboxylic acid ( soap ) , and glycerol
then if u want the Carboxyic acid from the Na salt, you do acid hydrolsis
hydrolysis is heating under reflux with either acid / alkali
Oh okay, umm so all alkaline hydrolysis will give you a sodium salt of carboxylic acid ?? Like ALWAYS? ???
-
also u have to know acid hyrolysis of proteins and starch ( carbs )
:o :o :o :o r u serious? can you please explain that? Thanks a lott.. :D
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Oh okay, umm so all alkaline hydrolysis will give you a sodium salt of carboxylic acid ?? Like ALWAYS? ???
alkaline hydrolosis of fat gives you glycers + the sodium salt ,yep and that is the soap !!!!!
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alkaline hydrolosis of fat gives you glycers + the sodium salt ,yep and that is the soap !!!!!
Oh ryte, thanks, :)
-
alkaline hydrolosis of fat gives you glycers + the sodium salt ,yep and that is the soap !!!!!
i see u have been studyin ..cool ....i hope u do well in ur exam ;)
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also u have to know acid hyrolysis of proteins and starch ( carbs )
Hydrolysis of proteins gives you Amino acids and hydrolysis of starch gives you glucose ryte? Lol i knew that, :P i just freaked out.. :P :P :P ;D
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:o :o :o :o r u serious? can you please explain that? Thanks a lott.. :D
look proteins ( polyamide ) + carbs ( polysacharide , starch ) , if u want to get the monomers ( repeating units ) , we use acid hydrolysis ( heat under refulux with dil. aq HCL )
for protien we get amino acids , for carbs we get monosacharide
but for fats , to get the monemers i.e carboxylic adn the glycers we use Alkalne hydrolsis then acid hydrolisis ( the opposite to the above^)
Si?
-
i see u have been studyin ..cool ....i hope u do well in ur exam ;)
yep im not done yet tho :/ + im just goin over the book and answering ppls qustions :P ( its helping me study !! )
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yep im not done yet tho :/ + im just goin over the book and answering ppls qustions :P ( its helping me study !! )
niether am i :-\ ... ya aha ::) lol :P ..it does help By the way :D
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look proteins ( polyamide ) + carbs ( polysacharide , starch ) , if u want to get the monomers ( repeating units ) , we use acid hydrolysis ( heat under refulux with dil. aq HCL )
for protien we get amino acids , for carbs we get monosacharide
but for fats , to get the monemers i.e carboxylic adn the glycers we use Alkalne hydrolsis then acid hydrolisis ( the opposite to the above^)
Si?
Ryte, Thanks a lot yet again. ;)
-
Guys, can someone explain the content of section 6.2 in the chemistry syllabus? bcuz i rlly dont get anything from it o.o' , plz ppl, any help? :o
-
Anyone can help me with Chemistry Oct/Nov 2009 P3, Q 5b, c (i) and (ii).
I'm really getting confused, and I'd appreciate an explanation on the whole hydride thing.
-
look proteins ( polyamide ) + carbs ( polysacharide , starch ) , if u want to get the monomers ( repeating units ) , we use acid hydrolysis ( heat under refulux with dil. aq HCL )
for protien we get amino acids , for carbs we get monosacharide
but for fats , to get the monemers i.e carboxylic adn the glycers we use Alkalne hydrolsis then acid hydrolisis ( the opposite to the above^)
Si?
are we required to know the molecular structures of fats, glycerol, fatty acids , soap compounds? how about the symbol formula (molecular)?
-
From which years are you guys solving from past papers =X ?
-
Hello ! ;D can anyone tell me what we're supposed to know about fuel cells and batteries ??? ???
-
Anyone can help me with Chemistry Oct/Nov 2009 P3, Q 5b, c (i) and (ii).
I'm really getting confused, and I'd appreciate an explanation on the whole hydride thing.
if u could pictuer the question and post it here it would be nice ! ill asnwer immediately
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From which years are you guys solving from past papers =X ?
i solved jun o2 till nov 07 ...i feel like that's way enough ...so hope u put a realistic range and do it ;)
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are we required to know the molecular structures of fats, glycerol, fatty acids , soap compounds? how about the symbol formula (molecular)?
well i know them but they arent in my book :/ so im not sure
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i solved jun o2 till nov 07 ...i feel like that's way enough ...so hope u put a realistic range and do it ;)
im doing from 2006-->2009 and more if i have time ... some people do from 1990 =.=" XD
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im doing from 2006-->2009 and more if i have time ... some people do from 1990 =.=" XD
these r ppl who have been workin on it since forever mate lol
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these r ppl who have been workin on it since forever mate lol
yeah , and they rarely repeat any questions.. and on our year .. the format changed.. that makes it awesome (Y) .. like math last year for me :@
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these r ppl who have been workin on it since forever mate lol
LIKE ME !!!!!!!!!!!!!!!!
-
https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
Here's the link posted by VIN. Sorry my net is really slow right now, I can hardly upload anything.
Here's my question.
Anyone can help me with Chemistry Oct/Nov 2009 P3, Q 5b, c (i) and (ii).
I'm really getting confused, and I'd appreciate an explanation on the whole hydride thing.
-
LIKE ME !!!!!!!!!!!!!!!!
lmao which years did you solve O_O ?
-
LIKE ME !!!!!!!!!!!!!!!!
y r u pissed off ??? lol ::)
-
can anyone tell me what we're supposed to know about fuel cells and batteries ???
Thanx in advance ;D
-
https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
Here's the link posted by VIN. Sorry my net is really slow right now, I can hardly upload anything.
Here's my question.
i see
HINT : COMPARABLE TO ALKANES !!! FORMULA OF ALKANES IS = CnH2N + 2 RIGHT?
and it says 4???
and it says hydride???
so just draw BUTANE and repace the 4 carbons by 4 Germanium atoms !
2. like combustion of alkanes , CO2 + H20, THIS TIME GEO2 + H20
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y r u pissed off ??? lol ::)
No, no. :D Why would I be angry ?
Just saying, I have done all P3's from 1990 to 2009. AND I FEEL GOOOOOOOOD ! :P
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No, no. :D Why would I be angry ?
Just saying, I have done all P3's from 1990 to 2009. AND I FEEL GOOOOOOOOD ! :P
lol ....
i kno that it feels great ;) lol :P
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No, no. :D Why would I be angry ?
Just saying, I have done all P3's from 1990 to 2009. AND I FEEL GOOOOOOOOD ! :P
wow man respect !:P
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No, no. :D Why would I be angry ?
Just saying, I have done all P3's from 1990 to 2009. AND I FEEL GOOOOOOOOD ! :P
If you dont get A* .. I KILL YOUUUU :D
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CHEMI HELP PLEASE
November 2002 Q1(a)(ii)
I dont get this thing because i just dont inderstand what yield means and the whole idea,, PLEASE HLEP
-
If you dont get A* .. I KILL YOUUUU :D
Believe me I will.
wow man respect !:P
My future depends on that chem exam. I cant mess up.
-
LIKE ME !!!!!!!!!!!!!!!!
are we required to know the molecular structures of fats, glycerol, fatty acids , soap compounds? how about the symbol formula (molecular)?
-
CHEMI HELP PLEASE
November 2002 Q1(a)(ii)
I dont get this thing because i just dont inderstand what yield means and the whole idea,, PLEASE HLEP
GO STUDY EQUILIBRIUM !
since the forward reaction is exothermic , if you increase the temperature ! equilbibrium will want to decrease the temperature ! ( it does the opposite of what u want ) and to decrease the the temperature , it moves in the endothermic direction ( opposite to the exothermic dircetion ) so equilibrium moves from right to left and so onow equilibrium is in the REACTANT SIDE AND SO reactants yield = amount , incrase and producti decrease , because its equilibrium if one increase the other has to decrease
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are we required to know the molecular structures of fats, glycerol, fatty acids , soap compounds? how about the symbol formula (molecular)?
NO !!! Just the names and products of hydrolysis.
-
Believe me I will.
My future depends on that chem exam. I cant mess up.
Well lets see , ima get top of the world ;)
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Believe me I will.
My future depends on that chem exam. I cant mess up.
u did good in p1 and p6?
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NO !!! Just the names and products of hydrolysis.
Amazing :P so not even the formulas ??
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GO STUDY EQUILIBRIUM !
since the forward reaction is exothermic , if you increase the temperature ! equilbibrium will want to decrease the temperature ! ( it does the opposite of what u want ) and to decrease the the temperature , it moves in the endothermic direction ( opposite to the exothermic dircetion ) so equilibrium moves from right to left and so onow equilibrium is in the REACTANT SIDE AND SO reactants yield = amount , incrase and producti decrease , because its equilibrium if one increase the other has to decrease
Im sorry i just dont get why the yield increses when equilibrium shifts from right to left.. will you please explain.
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can u pls write the catalyst that we should know for paper3 ?
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can u pls write the catalyst that we should know for paper3 ?
Finely divided iron for HABER PROCESS 450C 200 atm
Vanadium(V)Oxide for Contact process 450C 2atm
For cracking Alkanes - Al2O3/SiO2 and 500C and 10-12 atm
thats all i can remember now maybe im missing some reactions!
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Guys, any help/tips for Chemistry Paper 3? I'm not at all well-prepared. I'm talking about notes, etc.
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Im sorry i just dont get why the yield increses when equilibrium shifts from right to left.. will you please explain.
look , right now the forward reaciton is exothermic , so imagine u are heating so u are producing more of teh S03
so wherever equilibrium is , the side , reactants or products INCREASE ! , right now it is hight temp and so u go to exothermic direction and so equilbrium is at the RIGHT
but now if u decrese the temp that means you are cooling that means u are movin in the endothermic direction to cool
so from left to right
get it?
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Finely divided iron for HABER PROCESS 450C 200 atm
Vanadium(V)Oxide for Contact process 450C 2atm
For cracking Alkanes - Al2O3/SiO2 and 500C and 10-12 atm
thats all i can remember now maybe im missing some reactions!
thx. if u remember more can u pls write again ?
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thx. if u remember more can u pls write again ?
sure!
-
look , right now the forward reaciton is exothermic , so imagine u are heating so u are producing more of teh S03
so wherever equilibrium is , the side , reactants or products INCREASE ! , right now it is hight temp and so u go to exothermic direction and so equilbrium is at the RIGHT
but now if u decrese the temp that means you are cooling that means u are movin in the endothermic direction to cool
so from left to right
get it?
Yeah i get it! thanks you very much! :)
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@ aangel42:
Checkout the question paper from past papers. The answer sheet - it's this single paper numbered from 1-40. Next to each number, there are 4 tiny rectangles, lebelled A B C and D. For example, answer to question 1, is A. You colour inside the rectangle next to 1, labelled A.
You have to use HB pencil. Doesn't matter mechanical pencil or not. Main thing - it's an HB pencil. Best to carry 2-3 pencils. Carry an eraser too. :) Don't worry. All instructions are on the paper. It'll be fine. No worries. :)
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ppl im not able to download the answer paper of chemistry paper3 june 2004. can some1 download and attach it 4 me?
-
HERE !
-
HERE !
thx !!
-
thx !!
np ;)
-
np ;)
ur done studying and past papers ?
-
Fractional distillation of liquid air - HELP PLEASE!
Can someone post a link about it or so?
-
ur done studying and past papers ?
Just going through my TextBook now.
-
thx !!
And also Adding H2 to Alkenes .. Ni 200C
And Subs. with alkanes - UV light
And the reaction between Alcohol + Acid -->Ester + water .. condition hot C.Sulphuric acid
and Adding Steam to Alkenes Either Sulphuric acid 80C / Phosporic acid 300C and 70 atm
if i remember more ill tell you
-
Anyone Drew this??
can't get the first, want to make sure of the second
-
1 more Plzz, Whats with 09 and drawing :P
-
how do we know which reagent is in excess??
and how do u solve the fourth question??
-
how do we know which reagent is in excess??
and how do u solve the fourth question??
i) 8/64=0.125
ii) 14.2/71=0.2
iii) SO2 (The one which isn't in excess is the one with the least no. of moles)
iv) 0.125 (We use moles of limiting reagent)
v) 0.125*135=16.9g
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https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
Here's the link posted by VIN. Sorry my net is really slow right now, I can hardly upload anything.
Here's my question.
Anyone can help me with Chemistry Oct/Nov 2009 P3, Q 5b, c (i) and (ii).
I'm really getting confused, and I'd appreciate an explanation on the whole hydride thing.
I still don't get it. Anyone can help?
-
I still don't get it. Anyone can help?
You don't need to know about hydrides. They tell you in the question: they are comparable to alkanes.
So, you just draw the structual formula of Ge4H10 (alkane would be C4H10).
We know products of combustion of alkanes are carbon dioxide and water, so simply for these hydrides it's germanium (IV) oxide and water.
-
how do we know which reagent is in excess??
and how do u solve the fourth question??
? Because they say grams we have to assume the Cl2 and S02 are solids not gases
right?
-
? Because they say grams we have to assume the Cl2 and S02 are solids not gases
right?
Yes.
-
aqueous refers to dilute ... as in it contains a high concentration of water molecules.
-
Yes.
Ok got it Thanks,,
In calculations of moles is there a fixed rounding point,
like 2 d.p ,
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Ok got it Thanks,,
In calculations of moles is there a fixed rounding point,
like 2 d.p ,
Doesn't really matter as long as you keep it constant. So use 2dp throughout or 3sf, you choose! ;)
-
aqueous refers to dilute ... as in it contains a high concentration of water molecules.
Not exactly .. Aq. means that the solvent is water ( i.e its disolved in water) it can STILL be CONCETRATED.
-
how do we know which reagent is in excess??
and how do u solve the fourth question??
firstly you have to calculate the number of moles and which ever has the most moles is the one in excess for example in the may june 2oo4 exam its between magnesium and ethanoic acid... u calculate the original number of moles ... n(Mg)= 3/24 = 0.125 AND of ethanoic acid = 0.2 mole ... this is considered the orginial the amount of moles u placed in the solution or reaction.. then u will say Mg is in excess because Mg can only react with 2*0.125 moles of ethanoic acid which is 0.25 hence Mg is in excess get it?
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Not exactly .. Aq. means that the solvent is water ( i.e its disolved in water) it can STILL be CONCETRATED.
Yeah I can see what you're saying.. but you can relate (in a weird way :P) to urine when its dilute and when its concentrated u become constipated because there isnt enough water in ur system and fibre but thats not the point... In the chemistry study guide, most of the aqueous solutions have the same products or perhaps better to say ions H+ and OH- as dilute solutions ( unless they are transition elements or something like that)
-
So can anyone draw or find???
-
So can anyone draw or find???
Draw/Find what?
-
Draw/Find what?
By short,
Silicon carbide
Dimethyl sulphide, Germanium (IV) oxide,
Anyone Drew this??
can't get the first, want to make sure of the second
and
1 more Plzz, Whats with 09 and drawing :P
[/quote
PLZ :D
-
Fractional distillation of liquid air - HELP PLEASE!
Can someone post a link about it or so?
Fractional distillation of liquid air is a process used to separate liquids with different boiling points
this process is carried out in a fractioning column
Fractional Distillation of petrolleum:-
Natural Gas- for cooking
Gasoline-car fuel
Naphtha-for chemical industries
Kerosene-fuel in jet engines
Diesel Oil-fuel in diesel engines
Fuel Oil-fuel in ships
Lubricating oil-used in waxing and lubricating
Bitumen-for paving roads and isolation
As we go down the fractioning column frm natural gas to bitumen, the boiling point increases gradually.
Hope tht helped ;D
-
By short,
Silicon carbide
Dimethyl sulphide, Germanium (IV) oxide,
and
1 more Plzz, Whats with 09 and drawing :P
[/quote
PLZ :D
Rest coming up.. (hope its not too compli.)
-
the other..
-
here..
-
here..
The structural formula of anything is the one showing the bonds and the display is like CH3-CH bla bla
??
-
The structural formula of anything is the one showing the bonds and the display is like CH3-CH bla bla
??
You are not making sense; please be more precise.
-
And By the way The polymer formed by HO-CH2CH2-OH and
HOOC-C6H4-COOH shouldnt it be OC-C6H4-COO-CH2CH2-O ?
The alcohol looses H and the acid looses - OH
The MS says :
-OOC-C6H4-COOCH2CH2O- =_="
Where did the first extra O come from >_> or its just a part of the last monomer?
-
You are not making sense; please be more precise.
When they ask for Structural formula ...Which one do you draw/write .. The one with ALL THE BONDS or in this form CH3-CH2-CH2..etc
This is what i mean by all bonds
H H
H-C -C-H or do we write it in this form CH3-CH3 or its the same ::)
H H
-
i) 8/64=0.125
ii) 14.2/71=0.2
iii) SO2 (The one which isn't in excess is the one with the least no. of moles)
iv) 0.125 (We use moles of limiting reagent)
v) 0.125*135=16.9g
thx...
so the one with most moles means it's excess??always?
and the fourth one i still dont get it.... :'(
-
When they ask for Structural formula ...Which one do you draw/write .. The one with ALL THE BONDS or in this form CH3-CH2-CH2..etc
This is what i mean by all bonds
H H
H-C -C-H or do we write it in this form CH3-CH3 or its the same ::)
H H
Actually, I am not sure :P When they you give a big space I draw the displayed formula AND write the condensed one (CH3-CH3)
-
Actually, I am not sure :P When they you give a big space I draw the displayed formula AND write the condensed one (CH3-CH3)
mmkkay and can you look at my other question about the polymer , thanks!
-
Got a doubt from the 2005 m/j paper 3 chemistry paper.
When 0.015 moles of iodine react with 0.045 moles of chlorine to form 0.030 moles of a single product. So, we have to complete the equation. The answer is:
I2 + 3Cl2 = 2ICl3 my question is how come theres 3 atms of Cl formed?
Oh and second question....when iodine reacts with zinc nd wen u decrease the concentration of iodine how come less of zinc is used up?
-
yet another..
Thanks dude..
so i can just draw it like
o
l
o-Ge-o
l
o
-
QUESTIIIOON!!
balance the ionic equation By the way scandium fluoride and calcium:-
...Ca+...Sc3+ --> ...Ca2+ +...Sc
-
QUESTIIIOON!!
balance the ionic equation By the way scandium fluoride and calcium:-
...Ca+...Sc3+ --> ...Ca2+ +...Sc
3..Ca+.2..Sc3+ --> 3...Ca2+ +.2..Sc
there has to be same maount of electrons on each side , therefore we make it 6 -->6
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Guys, a silly doubt :P Whats the difference between Heat, Roast and burn in air.. ??? Thanks.
-
3..Ca+.2..Sc3+ --> 3...Ca2+ +.2..Sc
there has to be same maount of electrons on each side , therefore we make it 6 -->6
The polymer formed by HO-CH2CH2-OH and
HOOC-C6H4-COOH shouldnt it be OC-C6H4-COO-CH2CH2-O ?
The alcohol looses H and the acid looses - OH
The MS says :
-OOC-C6H4-COOCH2CH2O- =_="
Where did the first extra O come from >_> or its just a part of the last monomer?
-
Got a doubt from the 2005 m/j paper 3 chemistry paper.
When 0.015 moles of iodine react with 0.045 moles of chlorine to form 0.030 moles of a single product. So, we have to complete the equation. The answer is:
I2 + 3Cl2 = 2ICl3 my question is how come theres 3 atms of Cl formed?
Oh and second question....when iodine reacts with zinc nd wen u decrease the concentration of iodine how come less of zinc is used up?
sincec ration is 1 : 3 : 2
and we normally get ICL
but since it is 2 ICL , we have have now 2 i odines and 2 chlorines
now we have to balance , 2 iodines on the left :D
but thre are 6 clhorines on the left and honly two on the right , so we have to change the cl into CL3
less concentraion = less molecules per unite volume , less molecules = less reaction , so less zinc gets used up
-
Guys, a silly doubt :P Whats the difference between Heat, Roast and burn in air.. ??? Thanks.
All the same......
-
The polymer formed by HO-CH2CH2-OH and
HOOC-C6H4-COOH shouldnt it be OC-C6H4-COO-CH2CH2-O ?
The alcohol looses H and the acid looses - OH
The MS says :
-OOC-C6H4-COOCH2CH2O- =_="
Where did the first extra O come from >_> or its just a part of the last monomer?
the alcohol jst loses an H
which paper ?
-
3..Ca+.2..Sc3+ --> 3...Ca2+ +.2..Sc
there has to be same maount of electrons on each side , therefore we make it 6 -->6
umm...but 2 on Sc when its valency is 3??!
i just dont get this ionic eq balancing!
-
In may/june 2003 paper 3 chemistry how do you draw the structure of the polymer? its questions 3d(ii)
-
the alcohol jst loses an H
which paper ?
errm let me see . 2004 nov!
-
umm...but 2 on Sc when its valency is 3??!
i just dont get this ionic eq balancing!
its 3+ on th eleft and 2 + on the right , so we have to make it 6 to balance
so times 3+ by 2 and 2 + by 3 = 6
and snce now you have 2 SC 3+ oyu have to 2 SC atoms!
-
errm let me see . 2004 nov!
the C00 is a double bond
its right
-
its 3+ on th eleft and 2 + on the right , so we have to make it 6 to balance
so times 3+ by 2 and 2 + by 3 = 6
and snce now you have 2 SC 3+ oyu have to 2 SC atoms!
ohkk!
got it!
thanks!
+rep! ;)
-
In may/june 2003 paper 3 chemistry how do you draw the structure of the polymer? its questions 3d(ii)
link please
-
the C00 is a double bond
its right
How is it correct O_O .. The acid looses -OH .. which makes it -OC ? im quiet sure..
I know that there is a double bond between the C and O but that doesnt mean there is 2x O .. its -OC ?
-
How is it correct O_O .. The acid looses -OH .. which makes it -OC ? im quiet sure..
I know that there is a double bond between the C and O but that doesnt mean there is 2x O .. its -OC ?
TELL US WHICH YEAR THIS IS FROM !!!!
-
How is it correct O_O .. The acid looses -OH .. which makes it -OC ? im quiet sure..
I know that there is a double bond between the C and O but that doesnt mean there is 2x O .. its -OC ?
If anyone can help here ? look at my question:
The polymer formed by HO-CH2CH2-OH and
HOOC-C6H4-COOH shouldnt it be OC-C6H4-COO-CH2CH2-O ?
The alcohol looses H and the acid looses - OH
The MS says :
-OOC-C6H4-COOCH2CH2O- =_="
Where did the first extra O come from >_> or its just a part of the last monomer?
Confirm whos correct please :)
asap :P
-
TELL US WHICH YEAR THIS IS FROM !!!!
I think ive posted which year >_> 2004 nov =_="
-
How is it correct O_O .. The acid looses -OH .. which makes it -OC ? im quiet sure..
DRAW IT
-C0 is a double bond and it bonds to an 0
i always draw it i dotn like tht funny formula
-
thx...
so the one with most moles means it's excess??always?
and the fourth one i still dont get it.... :'(
ivo??anybody? :'(
-
TELL US WHICH YEAR THIS IS FROM !!!!
Dont get blinded by anger :p
-
less concentraion = less molecules per unite volume , less molecules = less reaction , so less zinc gets used up
ya, but the same amount of product is formed wid either high or low conc. so wont usin less of reactant give you less of product?
-
It's not that I'm bad at balancing just had difficulties
doing this one ;)
-
ya, but the same amount of product is formed wid either high or low conc. so wont usin less of reactant give you less of product?
WRONG
concentraion affects the amount of product ! but yeh less reactant will give u less product :/ ur sayin opposite to wht u said
-
DRAW IT
-C0 is a double bond and it bonds to an 0
i always draw it i dotn like tht funny formula
Okay ill draw it ...
O O
ll ll
----(---C ---[C6H4]---C-O-[CH2CH2]-o--)n----
-
Okay ill draw it ...
O O
ll ll
----(---C ---[C6H4]---C-O-[CH2CH2]-o--)n----
-
Okay ill draw it ...
O O
ll ll
----(---C ---[C6H4]---C-O-[CH2CH2]-o--)n----
The double bond O is ontop of the C ..
-
yes the sceond C shoudl have a double bond with O and it should also be connected to another O
THE -C0 is a double bond AND SO C00 makes it connected to another 0
get me?
-
ivo??anybody? :'(
Yes when having a balanced equation it's a ratio..
Get it, i can post an example :)
-
yes the sceond C shoudl have a double bond with O and it should also be connected to another O
THE -C0 is a double bond AND SO C00 makes it connected to another 0
get me?
I stil dont get it , is my diagram correct though?
-
I m drawing it on MS Paint - HANG ON !
-
I stil dont get it , is my diagram correct though?
and im talking about the first C mate .. shouldnt it be bonded to only one O as in the diagram i did?
Maybe your talking about the second C which i know has one double bond with an O and another single bond with another O
-
nop wrong
-
nop wrong
Okay lets wait for Ari's diagram then >_<
-
Okay lets wait for Ari's diagram then >_<
oki doki
-
Its should be this :
-
Its should be this :
<3
but u dont hav ot extend the C6H4 and the C2H4 :/ but its up to u
-
WRONG
concentraion affects the amount of product ! but yeh less reactant will give u less product :/ ur sayin opposite to wht u said
umm...actually concentration affects the time it takes to form the product provided evrythin else remains the same! :)
so amount of product formed always remains the same!!!! (textbuk is in my face, and buks dont lie!) 8) 8) :P
oh...umm...By the way i got it!!!!!thanks!!!!! ;D ;D
-
<3
but u dont hav ot extend the C6H4 and the C2H4 :/ but its up to u
So my diagram was correct after all .......?
ugh you scared me .. and my question was.. do you see the C double bond O at the begining .. ? This makes it -OC but the MS wrote -OOC.. but my diagram is correct so screw the MS
-
<3
but u dont hav ot extend the C6H4 and the C2H4 :/ but its up to u
LOL !!!
True what you say about extending the chain, but then again..... why take the risk ?
-
LOL !!!
True what you say about extending the chain, but then again..... why take the risk ?
Whats the hardest exam between 1993-2002?
Ill solve one of them then im done >_>
-
umm...actually concentration affects the time it takes to form the product provided evrythin else remains the same! :)
so amount of product formed always remains the same!!!! (textbuk is in my face, and buks dont lie!) 8) 8) :P
oh...umm...By the way i got it!!!!!thanks!!!!! ;D ;D
it depends , if u use a higher concntaion with same amoutn of zinc , thn the product is same
but if zinc was in excess if u increase concentratin u increase product
-
Can someone please draw the structure of the alloy BRASS :)
-
metal+water=metal hydroxide the hydrogen? in summer 2003 p3 it says its metal hydroxide and hydrogen but why not metal oxide?theyre talking about metals caesium barium and lanathium
-
metal+water=metal hydroxide the hydrogen? in summer 2003 p3 it says its metal hydroxide and hydrogen but why not metal oxide?theyre talking about metals caesium barium and lanathium
Any metal Above Ca reacts to give a hydroxide and H2.. im talking about the order in reactivity series..
-
All the same......
THANKSS.. ;D
-
Yes when having a balanced equation it's a ratio..
Get it, i can post an example :)
what the hell r u talking abt??
-
Can someone please draw the structure of the alloy BRASS :)
(http://gcsesciencealive.co.uk/images/Alloy%20structures.jpg)
^^Basically for ALL alloys(depending upon number of metals), By the way you don;t have to know the structures.
-
Guys, a silly doubt :P Whats the difference between Heat, Roast and burn in air.. ??? Thanks.
Roasting in air (just means heating very strongly in air).
Heating is not as strong as roasting (by miles).
-
Any metal Above Ca reacts to give a hydroxide and H2.. im talking about the order in reactivity series..
I dont know the place for caesium and lanathium in the reactivity series
-
By the way you don;t have to know the structures.
I saw this question in O/N 2002 03, Q 4 (ii) ::)
-
By the way, for some questions they ask how to concentrate something (eg aqeous ethanol). What does it mean, like add more acid to concentrate, or remove water?
Also, what does saturated solution mean? I don't mean the stuff about alkanes, the other definition.
-
link please :/
-
By the way, for some questions they ask how to concentrate something (eg aqeous ethanol). What does it mean, like add more acid to concentrate, or remove water?
Also, what does saturated solution mean? I don't mean the stuff about alkanes, the other definition.
you havae to evaporate the water (in case of ethanol i think u have to use fractional distillation )
sat solution means contains maximum amount of solute in a solvent( or maximum amoutn of dissolved material ) in a particulare temprature
-
what the hell r u talking abt??
Here, check this example.When iron reacts with sulphur the equation is
Fe + S --> FeS
This indicates that we need equal numbers of atoms iron and sulphur to react.
It is known that 1 mol of iron (56g) and 1 mol of sulphur (32g) contain the same number of atoms.
So reacting these amounts should give 1 mole of iron(ll)sulphide (88g). look at equation
Fe + S ---> FeS
1mol 1mol 1mol
56g 32g 88g
they can be scaled down, however they mmust always be ratio 56:32
thus
Fe + S ---> FeS
5.6g 3.2g 8.8
If we tried to 5g of S with 5,6 of iron the excess sulphur would remain unreacted
only 3.2g of sulphur will react. Sulphur is excess omm...
;) most important thing is that the reaction does not require a catalyst :P
-
NOV 09 p3 q4c and 5b PLZ AND Thank You IN ADVANCE :)
-
NOV 09 p3 q4c and 5b PLZ AND Thank You IN ADVANCE :)
both asnwrs have been discussed befre , if u go back a few pages ull find them!
-
NOV 09 p3 q4c and 5b PLZ AND Thank You IN ADVANCE :)
They have been solved by vin
here they are https://studentforums.biz/index.php/topic,1411.2820.html
In this past paper there are 4 drawing questions ;)
-
both asnwrs have been discussed befre , if u go back a few pages ull find them!
ur 777th post lol :D
-
ur 777th post lol :D
beoign 777 8)
i think that exists ^
-
It's not that I'm bad at balancing just had difficulties
doing this one ;)
So can anyone bother doing this, I got an answer which is correct,
But found it different that the marking scheme.
-
C4H9OH + 6O2 ==> 4CO2 + 5H2O
-
So can anyone bother doing this, I got an answer which is correct,
But found it different that the marking scheme.
C4H9OH + 6O2 ----> 4CO2 + 5H2O
yup whats the answer given?
-
So can anyone bother doing this, I got an answer which is correct,
But found it different that the marking scheme.
1 ... 6...4....5
yeah u guys are right :p
-
Yup thats right ;D
there anything wrong here..v
2C4H9OH + 11.75O2---->8CO2 + 9.5 H2O
Anyways Thanks A@di, Vin n Kimo :D
-
Right, my major(est) doubt so far. Cropped up in many papers before, but for one example, w02, Q2) c) ii). I don't understand any of the concentration, temperature stuff and sketching graphs. Cos everytime they have a different y-axis, and sometimes they say same volume of oxygen level, sometimes it doubles. Can someone please explain a general rule.
Many thanks in advance; I'm sweating over this! :o
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https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
Q 7-a (i)
In the MS it's written "an equation that gives: alkene + alkane or alkene + alkene + hydrogen"
Why is that. Cracking of alkanes --> alkene + hydrogen not alkene + alkane
-
https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
Q 7-a (i)
In the MS it's written "an equation that gives: alkene + alkane or alkene + alkene + hydrogen"
Why is that. Cracking of alkanes --> alkene + hydrogen not alkene + alkane
crackin of alkanes can be also used to produce hydrogen
-
^Trust me. I know that very well. That's not my question. Why is it alkene + alkane + hydrogen
-
Yup thats right ;D
there anything wrong here..v
2C4H9OH + 11.75O2---->8CO2 + 9.5 H2O
Anyways Thanks A@di, Vin n Kimo :D
umm yeah its wrong ..we just did it for u :/
-
^Trust me. I know that very well. That's not my question. Why is it alkene + alkane + hydrogen
dunno :O
-
^Trust me. I know that very well. That's not my question. Why is it alkene + alkane + hydrogen
How can that be?
All cracking reactions Give:
1) An Alkane with a shorter chain than the original, and a short chain Alkene
2)or two or more alkenes and hydrogen.
-
i need help with May/June 2009
Q3b.
i have attached it..
Please help!!
-
Can someone draw for me an isomer for pentan-1-ol CH3-CH2-CH2-CH2-CH2-OH
-
Can someone draw for me an isomer for pentan-1-ol CH3-CH2-CH2-CH2-CH2-OH
PENTAN -2-OL
JUST PUT THE OH on the second CH2
-
Can someone draw for me an isomer for pentan-1-ol CH3-CH2-CH2-CH2-CH2-OH
OH
|
CH3- CH-CH2-CH2-CH3
There, :)
-
OH
|
CH3- CH-CH2-CH2-CH3
There, :)
That makes sense, thank u
-
That makes sense, thank u
remember to write the name
PENTAN-2-OL
-
you guys when they tell us to describe a way to make a salt like lead nitrate, how do we know which one to put in excess, the lead oxide or the nitric acid??
-
you guys when they tell us to describe a way to make a salt like lead nitrate, how do we know which one to put in excess, the lead oxide or the nitric acid??
lead oxide afcourse , because we want aall the nitric acid to be used up , thne we filter to remove the excess lead oxide and we evaporate the filtrate for obtaining crystals
-
That makes sense, thank u
No Probs, Glad to help.. :)
-
Its always the insoluble substance which is the lead oxide in your case .. so you can filter it off .. its just a way of making sure all nitric acid reacted :D
-
lead oxide afcourse , because we want aall the nitric acid to be used up , thne we filter to remove the excess lead oxide and we evaporate the filtrate for obtaining crystals
why don't we want all the acid to be used up? ::) plus sometimes they say add excess acid dont they?
-
https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
Q 7-a (i)
In the MS it's written "an equation that gives: alkene + alkane or alkene + alkene + hydrogen"
Why is that. Cracking of alkanes --> alkene + hydrogen not alkene + alkane
https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
Q 7-a (i)
In the MS it's written "an equation that gives: alkene + alkane or alkene + alkene + hydrogen"
Why is that. Cracking of alkanes --> alkene + hydrogen not alkene + alkane
I can't really understand your question. Really ambiguous language. Well answering what I can grasp.
Lady lets put it like this. Here its decane and you have to give butene. Now after that, you've got six carbons and 14 hydrogens. So you can make anything in the world that you like from them. You can simply make it hexane or if you like hydrogen, you can make it hydrogen and hexene. That's why there are only two combinations, that you've already stated because you have to produce butene.
If butene wasn't stated, then you can make ethene, propane and pentene.
Basically, what I'm trying to state is that you must make an alkene from cracking. After that, you can make anything from the remaining stuff. Say if you want to crack ethane, then you can make ethene and hydrogen. Only 2 products are formed. You don't get an alkane here.
-
why don't we want all the acid to be used up? ::) plus sometimes they say add excess acid dont they?
Well if you add excess acid for example , how can you remove the excess :P ? its liquid you cant really remove it :P
And remember here we are making salts .. so we want to just have the right amount of solution to evaporate then cool and filter.. so we can use excess oxide and remove it , then we have solution of equal moles of Lead ions and Nitrate ions.. but if you use excess acid you cant remove it so they wont be balanced.
And yeah sometimes they do use excess acid , thats when you want to react like a metal fully but not for getting salts :D
-
Its always the insoluble substance which is the lead oxide in your case .. so you can filter it off .. its just a way of making sure all nitric acid reacted :D
ahaa, well thanks alot :)
-
Well if you add excess acid for example , how can you remove the excess :P ? its liquid you cant really remove it :P
And remember here we are making salts .. so we want to just have the right amount of solution to evaporate then cool and filter.. so we can use excess oxide and remove it , then we have solution of equal moles of Lead ions and Nitrate ions.. but if you use excess acid you cant remove it so they wont be balanced.
And yeah sometimes they do use excess acid , thats when you want to react like a metal fully but not for getting salts :D
mhmm i see. thanks!
-
lead oxide afcourse , because we want aall the nitric acid to be used up , thne we filter to remove the excess lead oxide and we evaporate the filtrate for obtaining crystals
and thank you!
-
Got a doubt from the 2005 m/j paper 3 chemistry paper.
When 0.015 moles of iodine react with 0.045 moles of chlorine to form 0.030 moles of a single product. So, we have to complete the equation. The answer is:
I2 + 3Cl2 = 2ICl3 my question is how come theres 3 atms of Cl formed?
Oh and second question....when iodine reacts with zinc nd wen u decrease the concentration of iodine how come less of zinc is used up?
compare the mole ratio.
0.015 : 0.045
1 : 3
i : cl
-
oh and another qs, once i was solving past papers and they asked what the product would be when a metal (forgot which one) reacted with water. i thought it would give the hydroxide and hydrogen but instead it actually gave the oxide :S then with another metal, it gave the hydroxide. how can we tell which one forms with each metal?
-
Guys, this has been bugging me. In some papers, the mole concept Q, sometimes the easy way to solve the problems is to use something like the volume ratio is same as the mole ratio or something. Umm, what is this and when can we use this? Thanks a lot in advance. :)
-
oh and another qs, once i was solving past papers and they asked what the product would be when a metal (forgot which one) reacted with water. i thought it would give the hydroxide and hydrogen but instead it actually gave the oxide :S then with another metal, it gave the hydroxide. how can we tell which one forms with each metal?
Hmm .. look at this
K
Na
Li
Ca
Mg
Al
C
Zn
Fe
Pb
H
Cu
Ag
Okay thats the reactivity series .. as you go down reactivity decreases .. ANY METAL ABOVE Ca .. reacts with COLD water to form hydroxide and H2
Anything under it forms oxide and H2 :D
Hope i helped
-
Guys, this has been bugging me. In some papers, the mole concept Q, sometimes the easy way to solve the problems is to use something like the volume ratio is same as the mole ratio or something. Umm, what is this and when can we use this? Thanks a lot in advance. :)
thats when the equation involves only gases. then you can use mole volume ratio or whatever is called :P
-
Hmm .. look at this
K
Na
Li
Ca
Mg
Al
C
Zn
Fe
Pb
H
Cu
Ag
Okay thats the reactivity series .. as you go down reactivity decreases .. ANY METAL ABOVE Ca .. reacts with COLD water to form hydroxide and H2
Anything under it forms oxide and H2 :D
Hope i helped
you did thanks loads :D what abt calcium does it form a hydroxide or oxide?
-
thats when the equation involves only gases. then you can use mole volume ratio or whatever is called :P
Only gases huh? Lol, ryte, so in that case we can guess how much of something is formed (the volume) using the mole ratios? Thx.. :)
-
Guys, this has been bugging me. In some papers, the mole concept Q, sometimes the easy way to solve the problems is to use something like the volume ratio is same as the mole ratio or something. Umm, what is this and when can we use this? Thanks a lot in advance. :)
take this reaction for example:
2N2 + 3H2 -----> 2NH3
56g 6g 34g
Now you can use this for example if they tell you we gave you 5.6g of nitrogen.. how many grams will be produced of hydrogen
Then you can do this
56 6
5.6 x
then find X by .. (5.6*6)/56
The same can be done
If you change it
The mole ratio is simply the co-officent of the reactants and products
2 3 2
just follow the same if they give you a specific amount of moles of reactant/product!
-
why does acid and salt water speed up de rate of rusting
can sum1 plz answer this
ASAP
-
Yo, I needed to ask, why does water act as a base when Sulphuric Acid dissolves in it?
-
Hmm .. look at this
K
Na
Li
Ca
Mg
Al
C
Zn
Fe
Pb
H
Cu
Ag
Okay thats the reactivity series .. as you go down reactivity decreases .. ANY METAL ABOVE Ca .. reacts with COLD water to form hydroxide and H2
Anything under it forms oxide and H2 :D
Hope i helped
Umm, i remember seeing MgOH.. O.O :S
-
you did thanks loads :D what abt calcium does it form a hydroxide or oxide?
Hyrdoxide .. always remember lime water :P ..
-
Why is everyone misunderstanding it. Fine, let me rephrase the whole thing in a language that everyone can understand.
I know like hell that cracking goes like this [Alkanes --> Alkene + Hydrogen]. This part understood?
Now in the Mark scheme they say that the answer to my question should be Alkane --> Alkene + Alkane + Hydrogen.
Get it? Now I want to know why they stated Alkane as a product in cracking. I'm not asking for a miracle.
So here's the link, and I hope a sensible person can answer me.
https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
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Umm, i remember seeing MgOH.. O.O :S
IM 100% sure its MgO :P
-
Could someone please explain may june 09 paper 32 q 5 b
I know it's for instance K3PO4 or T3 PO4.. but the other 2 marks not quite so any help??
-
Why is everyone misunderstanding it. Fine, let me rephrase the whole thing in a language that everyone can understand.
I know like hell that cracking goes like this [Alkanes --> Alkene + Hydrogen]. This part understood?
Now in the Mark scheme they say that the answer to my question should be Alkane --> Alkene + Alkane + Hydrogen.
Get it? Now I want to know why they stated Alkane as a product in cracking. I'm not asking for a miracle.
So here's the link, and I hope a sensible person can answer me.
https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
First chill off dude .. >_>
And Yes sometimes Alkane can be cracked to give SMALLER CHAIN ALKANE ... this is just HOW IT IS .. >_<
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@Larimeeva I strongly suggest lowering your tone; we are all here to help you, but we are NOT OBLIGED to help you.
Respect others and treat them fairly; most importantly be NICE.
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IM 100% sure its MgO :P
Hehe Wikipedia doesnt think so.. :P :P
http://en.wikipedia.org/wiki/Magnesium_hydroxide
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First chill off dude .. >_>
And Yes sometimes Alkane can be cracked to give SMALLER CHAIN ALKANE ... this is just HOW IT IS .. >_<
And sometimes Alkane-->Alkene + Hydrogen or Alkene + alkane .. or Alkane+ hydrogen or alkane + alkene +hydrogen!
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Hehe Wikipedia doesnt think so.. :P :P
http://en.wikipedia.org/wiki/Magnesium_hydroxide
Ugh sigh :P , OFCOURSE Magnesium HYDROXIDE EXISTS OBVIOUSLY.. BUt where talking about the products when magnesium reacts with water .. its MgO :P sorry to disappoint you and your wiki :D
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Hyrdoxide .. always remember lime water :P ..
omg no it can form both! cuz there are diff types of lime :P slaked lime, quicklime, limestone
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@Larimeeva I strongly suggest lowering your tone; we are all here to help you, but we are NOT OBLIGED to help you.
Respect others and treat them fairly; most importantly be NICE.
my headphones almost blew my ears there ! thanks ari =.= :P :P
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Why is everyone misunderstanding it. Fine, let me rephrase the whole thing in a language that everyone can understand.
I know like hell that cracking goes like this [Alkanes --> Alkene + Hydrogen]. This part understood?
Now in the Mark scheme they say that the answer to my question should be Alkane --> Alkene + Alkane + Hydrogen.
Get it? Now I want to know why they stated Alkane as a product in cracking. I'm not asking for a miracle.
So here's the link, and I hope a sensible person can answer me.
https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
Lady the mark scheme I have gives two options. alkene + alkane OR alkene + alkene + hydrogen. Now butene is the alkene and you can then have alkane which is hexane!!! What is wrong with that?? You can have an alkane as a product! As long as an alkene is made cracking is happening!!!
Now if you want to add hydrogen to it, then its butene, hydrogen and hexene (aka alkene+alkene+hydrogen)!!! You cant have an alkane here.
I'm not doing a miracle :D :D :D...
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Only gases huh? Lol, ryte, so in that case we can guess how much of something is formed (the volume) using the mole ratios? Thx.. :)
yuup, learnt that from here too :P
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Ugh sigh :P , OFCOURSE Magnesium HYDROXIDE EXISTS OBVIOUSLY.. BUt where talking about the products when magnesium reacts with water .. its MgO :P sorry to disappoint you and your wiki :D
Lol i tot u were trying to say tht it doesnt exist.. :P hahaha.. XD
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omg no it can form both! cuz there are diff types of lime :P slaked lime, quicklime, limestone
Well it forms CaO :P just memorize it then :P
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take this reaction for example:
2N2 + 3H2 -----> 2NH3
56g 6g 34g
Now you can use this for example if they tell you we gave you 5.6g of nitrogen.. how many grams will be produced of hydrogen
Then you can do this
56 6
5.6 x
then find X by .. (5.6*6)/56
The same can be done
If you change it
The mole ratio is simply the co-officent of the reactants and products
2 3 2
just follow the same if they give you a specific amount of moles of reactant/product!
Thanks a lot.. ;D
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my headphones almost blew my ears there ! thanks ari =.= :P :P
LOL ! Okay, your welcome. The Lion exists to serve and protect his domain. ;)
I'm always watching.
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what conditions of rxns do we need to know other than contact and haber processes?
especially organic equations (e.g.cracking and polymerisation) do we need to know conditions for these?
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Yo, I needed to ask, why does water act as a base when Sulphuric Acid dissolves in it?
cuz it accepts a proton!! (H+) WOO :P
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Could someone please explain may june 09 paper 32 q 5 b
I know it's for instance K3PO4 or T3 PO4.. but the other 2 marks not quite so any help??
Could someone pleaaaaaaaase answer i quoted above ? :S??
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Could someone pleaaaaaaaase answer i quoted above ? :S??
YOu hvave to show that you know that the reaction ends at the 12 cm3 and the other i dont know :P i dont remember the question 8-)
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LOL ! Okay, your welcome. The Lion exists to serve and protect his domain. ;)
I'm always watching.
what conditions of rxns do we need to know other than contact and haber processes?
especially organic equations (e.g.cracking and polymerisation) do we need to know conditions for these?
-
what conditions of rxns do we need to know other than contact and haber processes?
especially organic equations (e.g.cracking and polymerisation) do we need to know conditions for these?
haber : 450C and 200 atm .. iron as catalyst ( Finely divided)
Contact: 450C 2 atm.. Vanadium (V) oxide
Cracking : Al2O3/SiO2 500C and 10-12atm
for adding H2O to ethene Phosphoric acid 300C 70 atm
For adding H2 to ethene Ni 200C
Correct me if im wrong!
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YOu hvave to show that you know that the reaction ends at the 12 cm3 and the other i dont know :P i dont remember the question 8-)
Here's the link may june 09 5 b pleaaaaaase explain..
www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_3.pdf
P 32
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Here's the link may june 09 5 b pleaaaaaase explain..
www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_3.pdf
P 32
It;s been solved earlier, i need to look..
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haber : 450C and 200 atm .. iron as catalyst ( Finely divided)
Contact: 450C 2 atm.. Vanadium (V) oxide
Cracking : Al2O3/SiO2 500C and 10-12atm
for adding H2O to ethene Phosphoric acid 300C 70 atm
For adding H2 to ethene Ni 200C
Correct me if im wrong!
are you quite sure thats all what we need to know?
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It;s been solved earlier, i need to look..
Thanks ill be waiting for ur explanation !
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Could someone please explain may june 09 paper 32 q 5 b
I know it's for instance K3PO4 or T3 PO4.. but the other 2 marks not quite so any help??
its T3(PO4)2 Since 8 cm3 of Na3PO4 react fully with 12 cm3 of nitrate of T. This means the molar ratio is 12:8 or 3:2
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"the vol. of phosphate soln used in cm3 is half the height of the ppt in mm
also at 8cm3 all the soln is used up. tht is because adding more does not increase the height of the ppt meaning there was no further reaction on adding more.
also the formula is T3(PO4)2-----because
u take it as 12cm3 of T nitrate react with 8cm3 of sodium phosphate (thts wen all the reactants r used up)
so.....12:8...simplify it
12:8
6:4
3:2
and therefore u get T3(PO4)2"
courtesy : mohit
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are you quite sure thats all what we need to know?
Yes .. if there are more ill post .. thats what came up to my mind at za moment :D
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Ok thanks much both but i asked for p 32 but i guess its the same thank :)
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Ok thanks much both but i asked for p 32 but i guess its the same thank :)
oh yea that one uses 6 cm3 instead of 8 but its the same method yes. you're welcomee :)
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Ok thanks much both but i asked for p 32 but i guess its the same thank :)
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Yes .. if there are more ill post .. thats what came up to my mind at za moment :D
dude, you sure we gotta learn ALL of that?! I've done lots of past papers and they've only ever asked for conditions for the contact and haber process :S
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dude, you sure we gotta learn ALL of that?! I've done lot's of past papers and they've only ever asked for conditions for the contact and haber process :S
What papers have you been doing :o This comes up ALL THE TIME !!
Are you core or extended ?
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dude, you sure we gotta learn ALL of that?! I've done lots of past papers and they've only ever asked for conditions for the contact and haber process :S
lol , haber comes oftenly along with contact .. but for the cracking i think you dont need to know what i typed until AS .. you can get the mark by stating heat and catalyst..
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What papers have you been doing :o This comes up ALL THE TIME !!
Are you core or extended ?
She means shes seen on contact and haber .. not that she never saw them.. read her post slowly :P
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lol , haber comes oftenly along with contact .. but for the cracking i think you dont need to know what i typed until AS .. you can get the mark by stating heat and catalyst..
Silicon (IV) oxide / Aluminium oxide catalyst to be exact ...
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Silicon (IV) oxide / Aluminium oxide catalyst to be exact ...
Ive said that :P look at my post before
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She means shes seen on contact and haber .. not that she never saw them.. read her post slowly :P
thanks xD
so we need to know the exact conditions for only haber, contact and..cracking?
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thanks xD
so we need to know the exact conditions for only haber, contact and..cracking?
Cracking if u want, ull still get the marks, :) But the conditions for habers and contacts, YES. :D
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thanks xD
so we need to know the exact conditions for only haber, contact and..cracking?
what rayoon said :D
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what rayoon said :D
Dude you're confusin me what do we need to know other than contact and haber process?
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i need help in section 6.2 of the syllabus! anyone? bcuz i get nothing from it ??? !
-
what tyoe of diagram do you draw when they ask for structural formula..
and wwhen is the other (one with branches and stuff) drawn?
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what tyoe of diagram do you draw when they ask for structural formula..
and wwhen is the other (one with branches and stuff) drawn?
You can draw either, like the CH3-CH2 thingi or the other full stucture showing all the bond one as well, its all up to you. :) I draw both just in case.. ;)
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also there are questions on "observe"
now we dont know colours of ALL compounds..
any tips to tackle this?
also is Nitrogen oxide and sulphur dioxide- colour?
and...
how does a nitrate decompose?
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also there are questions on "observe"
now we dont know colours of ALL compounds..
any tips to tackle this?
also is Nitrogen oxide and sulphur dioxide- colour?
and...
how does a nitrate decompose?
Umm, im guessing they will only give the Qs according to the syllabus.. they wont ask you anything out of the syllabus.
And, well, Most of the Nitrates decompose like this: 2Zn(No3)2 ---> 2ZnO + 4No2 + O2
BUT, Na and K decompose differently:
2KNo3 ---> 2KNo2 +O2
Na decomposes in a similar way..
:) Hope tht clears ur doubt.. :D
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also there are questions on "observe"
now we dont know colours of ALL compounds..
any tips to tackle this?
also is Nitrogen oxide and sulphur dioxide- colour?
and...
how does a nitrate decompose?
well , for compound su jst have to learn by heart
Nitrogen DIOXIDE is brown fumes
im not sure about sulfure dioxide but whn u burn sulfur in air it produces blue flame
group 1 nitrates ( EXCPT LITHIUM ) form EX: NANO3 --> NANO2 + 02 ( A NITRITE AND OXGYEN ) <---THIS IS NOT BALANCED
GROUP 2 + LI + TRANS METALS FORM EX l ZnNo3 ---> ZnO + nitrogen dixode + oxygen <---this is nto balancd
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what rayoon said :D
shukkraaaan (thank you :P)
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well , for compound su jst have to learn by heart
Nitrogen DIOXIDE is brown fumes
im not sure about sulfure dioxide but whn u burn sulfur in air it produces blue flame
group 1 nitrates ( EXCPT LITHIUM ) form EX: NANO3 --> NANO2 + 02 ( A NITRITE AND OXGYEN ) <---THIS IS NOT BALANCED
GROUP 2 + LI + TRANS METALS FORM EX l ZnNo3 ---> ZnO + nitrogen dixode + oxygen <---this is nto balancd
ohh..
last doubt!
s07 - q 7 b (i)
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how to draw this??
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ohh..
last doubt!
s07 - q 7 b (i)
DIOL DICARBOXYIL ACID
i cnt draw it sorry :/
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how to draw this??
yeh!
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DIOL DICARBOXYIL ACID
i cnt draw it sorry :/
what conditions of rxns do we need to know other than haber and contact?
-
yeh!
ask ARI
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how to draw this??
I have attached the first one.. :/ Someone please confirm if this is correct.. :)
IM working on the second.. :)
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Yep here u go.. :)
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I have attached the first one.. :/ Someone please confirm if this is correct.. :)
IM working on the second.. :)
terylene???? no totally wrong :/
i think i have the wrong paper
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Shoudnt this be it? because its but-2-ene
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terylene???? no totally wrong :/
No no, it was for catalyst.. :P his doubt.. :P
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Shoudnt this be it? because its but-2-ene
Yeah, im not too sure whether tht is ryte or the one i did.. :/ so can anyone please confirm on this? :)
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GUYS I HAVE TO GO NOW
GOODLUCK 2MRW ! ILL BE BACK 2NIGHT AND SEE IF I CAN ASNWER ANY QUESTIONS SO IF U WANT TO LEAVE ANY QUESTINS !
BBYE
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GUYS I HAVE TO GO NOW
GOODLUCK 2MRW ! ILL BE BACK 2NIGHT AND SEE IF I CAN ASNWER ANY QUESTIONS SO IF U WANT TO LEAVE ANY QUESTINS !
BBYE
GOOD LUCK! By the way what time is it at your place?
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GUYS I HAVE TO GO NOW
GOODLUCK 2MRW ! ILL BE BACK 2NIGHT AND SEE IF I CAN ASNWER ANY QUESTIONS SO IF U WANT TO LEAVE ANY QUESTINS !
BBYE
Yup, i have to go too.. :) GOOD LUCK TO EVERYONE FOR TOMORROW.. :P ITS 1:30 am here.. :P
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I have attached the first one.. :/ Someone please confirm if this is correct.. :)
IM working on the second.. :)
yeh its correct
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yeh its correct
Sweet.. ;D with tht happy tot, imma go sleep now.. ;D
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Shoudnt this be it? because its but-2-ene
the one you have drawn is 2-methyl-propene ( I don't really know what the chloride is called, but I'm sure the reactant is called 2-methyl-propene )
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can somebody confirm the answer??
m confused now...
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Yup, i have to go too.. :) GOOD LUCK TO EVERYONE FOR TOMORROW.. :P ITS 1:30 am here.. :P
Don't mind it lad but where do you live??? It's still 8:30 pm at my place lol :D...
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Yup, i have to go too.. :) GOOD LUCK TO EVERYONE FOR TOMORROW.. :P ITS 1:30 am here.. :P
Dude where do you live? China?
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can somebody confirm the answer??
m confused now...
haha dont be confused
both the answers by raywin are correct
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Dude where do you live? China?
Nope, Singapore.. :)
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can somebody confirm the answer??
m confused now...
Raywin is right ;)
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those graph questions...
on rate of reaction..
when does the FINAL volume change?
what conditions?
and when does the FINAL volume remain the SAME, even though the graph is steeper??!!
plz help out!! :-\ :-\ :-\ :-\
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those graph questions...
on rate of reaction..
when does the FINAL volume change?
what conditions?
and when does the FINAL volume remain the SAME, even though the graph is steeper??!!
plz help out!! :-\ :-\ :-\ :-\
Final volume changes when a different concentration is used/ reactant used in excess.
Final volume same when same concentration is maintained but a different reactant used/ a catalyst is used.
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those graph questions...
on rate of reaction..
when does the FINAL volume change?
what conditions?
and when does the FINAL volume remain the SAME, even though the graph is steeper??!!
plz help out!! :-\ :-\ :-\ :-\
Im guessing that the final volume only changes when the concentration changes? Ppl just see if this is ryte yeah.. ;)
And the final volume remains the same when the reaction is catalysed or increase in temperature.. :)
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@Ari: Ah, sorry, I didn't mean to sound that way, I was just a little frustrated.
I apologize again for causing chaos in your domain, my greatest apologize to anyone who I offended *bows*
@deadman786: So you're saying simply that this is true [Alkane --> Alkene + Alkane + Hydrogen]? If so, are there any rules for determining the products of this type of reaction?
My book doesn't state Alkane as a product, so it's a little confusing.
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@Larimeeva Its alright, we all make mistakes and I can understand your frustration. :)
Good luck with your exam and all the best ;)
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@Ari: Ah, sorry, I didn't mean to sound that way, I was just a little frustrated.
I apologize again for causing chaos in your domain, my greatest apologize to anyone who I offended *bows*
@deadman786: So you're saying simply that this is true [Alkane --> Alkene + Alkane + Hydrogen]?
My book doesn't state Alkane as a product, so it's a little confusing.
Let me give you an example..
Cracking of octane C8H18
H H H H H H H H H H H H H H H H H H
H- C - C- C- C -C -C -C -C -C -C-H ---> H-C- C- C- C- C-H + C =C- C-H + H2
H H H H H H H H H H H H H H H H H
(higher)Alkane Alkane + Alkene + H2
Octane Pentane Propene Hydrogen
got it?
-
i just wanted to say , i hope y'all includin me KILL >:( the paper tomorrow :D
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i just wanted to say , i hope y'all includin me KILL >:( the paper tomorrow :D
I wanna roast it in air! :P (sorry lame)
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^Yep, that makes sense completely. It kinda of splits up into two. One last confirmation, you wrote higher Alkanes so cracking of ethane gives ethene and hydrogen only since it's a lower hydrocarbon?
@Ari: Thank you.
-
I wanna roast it in air! :P (sorry lame)
nah it actually makes sense :)
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^Yep, that makes sense completely. It kinda of splits up into two. One last confirmation, you wrote higher Alkanes so cracking of ethane gives ethene and hydrogen only since it's a lower hydrocarbon?
@Ari: Thank you.
Yes. Products depends on how many carbon atoms the alkane being cracked contains.
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@Larimeeva Its alright, we all make mistakes and I can understand your frustration. :)
Good luck with your exam and all the best ;)
Ari do we have to know conditions of rxns other than contact and haber?
-
Could somene remind me if rust was oxidation or reduction please??
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I wanna roast it in air! :P (sorry lame)
Not lame - EPIC xD
I hope it's a good paper...I'm really worried about Chem :l
-
Ari do we have to know conditions of rxns other than contact and haber?
u need to kno crackin conditions as well as substitution reaction of alkAnes (halogenation)....... and addition polymerization
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Could somene remind me if rust was oxidation or reduction please??
Oxidation remember you reduce iron ore to form iron in a furnace
-
u need to kno crackin conditions as well as substitution reaction of alkAnes (halogenation)....... and addition polymerization
what are they for crackin and polymerisation?
Thanx in advance
-
what are they for crackin and polymerisation?
Thanx in advance
for cracking : the temp is 300 degree Celsius and the catalyst used is Alo3
oh and there is also Hydration : u add steam to ethene at abt 700 degree celcius , with the presence of a phosphoric catalyst and at 60 atmospheric pressure
addition ploy : 200 atmospheric pressure & 150 degree Celsius
hope i didn't forget anythin ....sure mate ;)
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Um, in my book for cracking its 540*C :-\ and yeah typo Al2O3 ;)
-
Um, in my book for cracking its 540*C :-\ and yeah typo Al2O3 ;)
it's okay ..main point that it has a high temp :P :P ..nah actually in my book it says 700 lol
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for cracking : the temp is 300 degree Celsius and the catalyst used is Alo3
oh and there is also Hydration : u add steam to ethene at abt 700 degree celcius , with the presence of a phosphoric catalyst and at 60 atmospheric pressure
addition ploy : 200 atmospheric pressure & 150 degree Celsius
hope i didn't forget anythin ....sure mate ;)
isnt there a catalyst for addition poly?
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Hmm, I'm pretty sure reaction invovling hydrogen happens at cathode and likewise for oxygen at the anode. I guess the diagram I chose was a bit weird, because if you look carefully, there are the - sign in hydrogen and + in oxygen.
My 'case' for this is also exemplified by this link:
http://inventors.about.com/od/sstartinventions/ss/Physics_Illustr_2.htm (http://inventors.about.com/od/sstartinventions/ss/Physics_Illustr_2.htm)
http://t1.gstatic.com/images?q=tbn:sT3pyEjo873ioM:http://205.153.241.230/issues/emergeoct2005/fuelcell.jpg
IT IS WRITTEN ANODE....! Told ya, it is not da same as eletrolysis which means yeah it would become negatively charged as electrons r lost by da H2 nd so flow from it to da other electrode. HOWEVER, it is da anode, da HYDROGEN FUEL CELL is different.....!
-
isnt there a catalyst for addition poly?
of what i know is that it does NOT
-
See this diagram. I found it pretty good. :)
CHeck this
https://studentforums.biz/index.php/topic,1744.msg136892.html#msg136892
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Could somene remind me if rust was oxidation or reduction please??
iron is reduced
-
Oxidation remember you reduce iron ore to form iron in a furnace
Thanks for the reminder xD
-
iron is reduced
Kay :)
Thank You
-
Um, in my book for cracking its 540*C :-\ and yeah typo Al2O3 ;)
450C-750C
-
In o/n 09 paper 32 q 6 c the total number of moles of gases why is it 0.08 i thought it would be 0.04 explain please quickly???
-
Here's the link 4 my question ...http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Nov/0620_w09_qp_32.pdf
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In o/n 09 paper 32 q 6 c the total number of moles of gases why is it 0.08 i thought it would be 0.04 explain please quickly???
first you find the moles of fe2o3 which is .08
and thn the ration of moles of gases = 2: 1 therfore .04
and there are two gases
so . 04 + .04
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first you find the moles of fe2o3 which is .08
and thn the ration of moles of gases = 2: 1 therfore .04
and there are two gases
so . 04 + .04
Fe2o3 is 0.04 not 0.08 .. soo?
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Fe2o3 is 0.04 not 0.08 .. soo?
sorry i meant fe2so4
12.16 /152
-
c)
1. 12.16/152 g= 0.08 moles
2. Molar ratio
= 2 : 1
= 0.08 : x
so x= 0.04
3. 56+56+16+16+16 = 160g
4. moles = mass/mass of 1 mole
mass = 0.04 * 160
=6.4g
5. two gases so 0.04 + 0.04 = 0.08mol
6. vol of gas = 0.08 * 24
= 1.92
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ok i have a silly question... :-[ s05 q2c (i)
how do u knw which one is in excess?
-
somebody pls explain to me this...
Hey Ya could someone pls do this question its really wierd cant figure it out at all
-
somebody pls explain to me this...
Hey Ya could someone pls do this question its really wierd cant figure it out at all
-
Hey Ya could someone pls do this question its really wierd cant figure it out at all
lol wheres the question?
-
Hey smart guy can u pls solve this question for me really cant understand it The link is just below this line.
Quote from: CatAly$t on June 05, 2010, 07:13:46 PM
c)
1. 12.16/152 g= 0.08 moles
2. Molar ratio
= 2 : 1
= 0.08 : x
so x= 0.04
3. 56+56+16+16+16 = 160g
4. moles = mass/mass of 1 mole
mass = 0.04 * 160
=6.4g
5. two gases so 0.04 + 0.04 = 0.08mol
6. vol of gas = 0.08 * 24
= 1.92
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Hey smart guy can u pls solve this question for me really cant understand it The link is just below this line.
Quote from: CatAly$t on June 05, 2010, 07:13:46 PM
c)
1. 12.16/152 g= 0.08 moles
2. Molar ratio
= 2 : 1
= 0.08 : x
so x= 0.04
3. 56+56+16+16+16 = 160g
4. moles = mass/mass of 1 mole
mass = 0.04 * 160
=6.4g
5. two gases so 0.04 + 0.04 = 0.08mol
6. vol of gas = 0.08 * 24
= 1.92
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ok i have a silly question... :-[ s05 q2c (i)
how do u knw which one is in excess?
OK look at the graph, mass of the plate is constant after some time. What does it mean? No more Zn is reacting, right? So the reaction is finished. Therefore Zn is excess as it is still left after the reaction is over. Got it?
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Hey Ya could someone pls do this question its really wierd cant figure it out at all
"the vol. of phosphate soln used in cm3 is half the height of the ppt in mm
also at 8cm3 all the soln is used up. tht is because adding more does not increase the height of the ppt meaning there was no further reaction on adding more.
also the formula is T3(PO4)2-----because
u take it as 12cm3 of T nitrate react with 8cm3 of sodium phosphate (thts wen all the reactants r used up)
so.....12:8...simplify it
12:8
6:4
3:2
and therefore u get T3(PO4)2"
courtesy : mohit123
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OK look at the graph, mass of the plate is constant after some time. What does it mean? No more Zn is reacting, right? So the reaction is finished. Therefore Zn is excess as it is still left after the reaction is over. Got it?
oh i see... Thanks :)
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ok gotcha thanks!!
"the vol. of phosphate soln used in cm3 is half the height of the ppt in mm
also at 8cm3 all the soln is used up. tht is because adding more does not increase the height of the ppt meaning there was no further reaction on adding more.
also the formula is T3(PO4)2-----because
u take it as 12cm3 of T nitrate react with 8cm3 of sodium phosphate (thts wen all the reactants r used up)
so.....12:8...simplify it
12:8
6:4
3:2
and therefore u get T3(PO4)2"
courtesy : mohit123
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i have urgent question in 2004 may june q 4 b iii i dnt get it at all and same paper 7 b (ii) in ms they rounded the 0.125 to 0.1 suppose it waz cuz they gave masses to 1 decimal why they didnt do the same in c (i) and (ii)
-
Attach the paper please
-
i don't know bout others, but i think i died in the examination room!!
ill be lucky to get a C. :'(
-
pls,
how to draw this??
-
Question 3a, How do you know which one is which and thanks! Good luck to you all people!
-
i don't know bout others, but i think i died in the examination room!!
ill be lucky to get a C. :'(
Whaat ?? :o what varient did you do ??
-
Question 3a, How do you know which one is which and thanks! Good luck to you all people!
working
-
Chem P3. It was okay. Not hard, but not easy either.
Wasn't too good for me, 'because I guess I didn't study enough. Those 9 days holz-ugh. :P
-
pls,
how to draw this??
anybody????
-
anybody????
Um, this should be right.
-
noble gas = D (cuz of 8 electrons in outermost shell...therefore a full shell)
soft metal = E (cuz all group I metals are soft)
covalent = F (cuz of being in group I and therefore form covalent bonds with group V)
giant structure = B (group IV form macromolecular structers)
ion = A ( group V form X3- ions
-
Um, this should be right.
at last... ;)
thx ;D
-
umm...no more questions?
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i have urgent question in 2004 may june q 4 b iii i dnt get it at all and same paper 7 b (ii) in ms they rounded the 0.125 to 0.1 suppose it waz cuz they gave masses to 1 decimal why they didnt do the same in c (i) and (ii)
^^ I'm sorry to say I'm too bored solving this ques. Plus I'm done with chem so I don't really feel like doing it now :P jk
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Was the paper easy?
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http://freeexampapers.com/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_3.pdf
Q5b.
I'm completely confused, and it obviously has something to do with stiochiometery which I'm really not good at. Anyone can help?
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http://freeexampapers.com/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_3.pdf
Q5b.
I'm completely confused, and it obviously has something to do with stiochiometery which I'm really not good at. Anyone can help?
This has been discussed a lot before.. :P BUT, here it is :
"the vol. of phosphate soln used in cm3 is half the height of the ppt in mm
also at 8cm3 all the soln is used up. tht is because adding more does not increase the height of the ppt meaning there was no further reaction on adding more.
also the formula is T3(PO4)2-----because
u take it as 12cm3 of T nitrate react with 8cm3 of sodium phosphate (thts wen all the reactants r used up)
so.....12:8...simplify it
12:8
6:4
3:2
and therefore u get T3(PO4)2"
courtesy : mohit
:D
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http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2008%20Nov/0620_w08_qp_03.pdf (http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2008%20Nov/0620_w08_qp_03.pdf)
yoyo :D Can anyone explain 4)b)ii) how is it possible that the mole ratio in mark scheme is 6:6 (1:1) when the percentage of carbon is 92.3 and Hydrogen is 7.7??
Thanks :D
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Guys, heres a Q that has been bothering me. :/ Does pollution affect the no. of organisms or the no. of species within tht polluted area? ??? ??? ???
Thanks, ;D
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Guys, heres a Q that has been bothering me. :/ Does pollution affect the no. of organisms or the no. of species within tht polluted area? ??? ??? ???
Thanks, ;D
what do u exactly mean.... with in that polluted area is right... but what do u mean with 'no. of organism' (without anything)
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what do u exactly mean.... with in that polluted area is right... but what do u mean with 'no. of organism' (without anything)
Hmm, like in a polluted area, does the pollution affect the number of organisms like for eg: due to pollution the no. of organisms reduced from 1000 to like 400, umm get it? Organisms like the total ones not looking at species here but general. and the other condition is does species reduce, for eg, the no. of species reduced from 10 to like 5. :/
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Hmm, like in a polluted area, does the pollution affect the number of organisms like for eg: due to pollution the no. of organisms reduced from 1000 to like 400, umm get it? Organisms like the total ones not looking at species here but general. and the other condition is does species reduce, for eg, the no. of species reduced from 10 to like 5. :/
Hmm... I think I've solved this one somewhere.. which year?
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Hmm... I think I've solved this one somewhere.. which year?
I did it long time ago, but I havent found it yet, i forgot the paper :/ but ill check which one it is and get back yeah.. :)
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How do you guys copy a question onto this forum using .png or whatever? idk how to.. lol
Well, anyway, can someone help me out with M/J 2007 Q18?
I think it's D. If humidity is low, the plant loses water. And if the light intensity is also low, the plant can't photosynthesize.
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easy, its C ofc. Temperature (by light intensity) increases, transpiration rate increases. Humidity low (less water mol. in amt. so water diffuses out)
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It's not, it's C. idk why, I picked D too.
And this is all the examiner report says: "This proved to be one of the more difficult questions on the paper, though it was noticeable that it was the able candidates who reasoned their ways to the correct response. Evident errors were shown by over a third of the candidates who thought that high humidity would cause wilting, and by well over half of them that thought low light intensity might be responsible for the condition."
Anyone solved this before and know why it's C? Thanks :)
See, humidity means a lot of water vapor is in the air around the plant. So, this reduces transpiration see? so thus, it will NOT wilt as transpiration is reduce. High light intensity will INCREASE transpiration. This could cause wilting as the plant might not be able to get as much water that is being lost to transpiration. Thus, the ans is C.
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Thank you to Raywin and Vin for taking the time to answer.
But yeah if humidity is reduced, transpiration is increased, I got that.
BUT if light intensity is LOW, doesn't that mean the plant won't be able to photosynthesize, which means it will wilt? Which means D could be right too?
OR ohhhh wait, low light intensity = low sunlight = low photosynthesis = plant turns YELLOW, it doesn't necessarily have to wilt, right?
So does that mean that ONLY a decrease in water causes wilting?
YES, photosynthesis will not make the plant wilt, its the water that flows through the stems that decide if the plant is wilting or not. :)
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Also, sorry guys, two more questions:
1) What is the gut? Is it the stomach or the intestine?
2) What are some common tissues the exam likes to test? I know this is stupid of me, but I get confused sometimes while differentiating between organs and tissues?
And, what score should be my aim if I want to get an A*?
Gut is the region bet the stomach and the anus.
Tissues are a group of SIMILAR cells working together. Organs are a group of similar tissues working together.
And an A*, it mainly depends on ur P3 performance. :)
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Ok thank you I get it now :)
So does less sunlight (reduced photosynthetic rate) cause the plant to turn yellow?
Or is that only because of reduced chlorophyll (meaning reduced, or no, magnesium ions)?
Light will just reduce the rate of photosynthesis. It is chlorophyll that gives the plant the green colour. And Mg is needed for chlorophyll synthtsis. So yes its the Mg deficiency that would make a plant turn yellow. :)
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thanks for all your help! +rep
anyone know how i can make the .png file where i can crop a part of the pdf and attach it to my post for you guys to download?
Np, ;D Glad to help. :)
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hey, who thought the CHEM P3 was a bit tough?
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thanks for all your help! +rep
anyone know how i can make the .png file where i can crop a part of the pdf and attach it to my post for you guys to download?
I have it in-built on my win7. Google "snipping tool" you'll get some links. ;)
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I have it in-built on my win7. Google "snipping tool" you'll get some links. ;)
Hahaha, lucky you, i have to do a screenshot, paste it on word and then crop it and then paste it on paint and edit and all tht and then save it as png thingi.. :P THEN i can attact it. :)
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hahaha, okay maybe i'll just attach the file each time and just say the question number
Does peristalsis work when one's lying down?
Hahaha, lol tht was a Q in a past paper ??? or curiosity? It does work even if ur upside down.. :P
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Hi guys i need help in Bio if possible in one of paper 1's (O/N 03) First question Link:http://freeexampapers.com/FreeExamPapers.com_.php?__lo=SUdDU0UvQmlvbG9neS9DSUUvMjAwMyBOb3YvMDYxMF93MDNfcXBfMS5wZGY=
Answer is :A So i guess plants excrete but what ??
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Hi guys i need help in Bio if possible in one of paper 1's (O/N 03) First question Link:http://freeexampapers.com/FreeExamPapers.com_.php?__lo=SUdDU0UvQmlvbG9neS9DSUUvMjAwMyBOb3YvMDYxMF93MDNfcXBfMS5wZGY=
Answer is :A So i guess plants excrete but what ??
O2 and/or CO2
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lol really? haha that's pretty cool :P just curiosity :D
WHY IS IT THAT I GET ALL OF THE HARD QUESTIONS RIGHT AND MESS UP ON THE EASY ONES???? >:( >:( >:( >:( >:(
Hahaha, lol it happens sometimess.. :P :P
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Okay guys, I realize this isn't anywhere in our syllabus, I'm just curious...
Why is it that when we don't eat for a while (like you barely ate anything for 12 hours), our stomach starts hurting because of hunger?
How is that possible?
If anyone has any idea.....
Lol, interesting Q, hmmm i think its because,
Normally our stomach produces HCl constantly. And well, when you dont eat for like 12 hrs like u said, the hcl umm builds up and its uncomfortable, which is why it hurts us. ;D hahaha.. i just gave it a try.. :P
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O2 and/or CO2
Ya that just slipped XD Thank You
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hey, who thought the CHEM P3 was a bit tough?
I did !
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ALL living organisms display those characteristics. Excretion isn't just..what you're thinking. lol :P
The syllabus defines excretion as: "the removal from organisms of toxic materials, the waste products of metabolism, and substances in excess of requirements (E.G. CARBON DIOXIDE)"
This is just one example, but plants respire, which means they use up oxygen and release CO2, same as humans do, and therefore they essentially excrete CO2.
I hope this helps?
HAHA yes thts what i was thinking :S
Ya it helped much Thanks u already have by now +rep :)
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Okay guys, I realize this isn't anywhere in our syllabus, I'm just curious...
Why is it that when we don't eat for a while (like you barely ate anything for 12 hours), our stomach starts hurting because of hunger?
How is that possible?
If anyone has any idea.....
Hurting or "growling"? You know the muscle stomach churns partially digested food or chyme. So this churning of mixture of solid and liquid food and gases produces sound, which is too low that's is why you cant hear the noise when your stomach is full. If your stomach is empty the noises are louder so you can hear them. Um, a practical experiment. Fill a bottle with 6-7 beads. Shake it, produces sound. Fill the bottle with beads till the bottle neck, shake. No sound. That is what prolly happening.
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Hello again.
O/n 03 Link :http://www.freeexampapers.us/IGCSE/Biology/CIE/2003%20Nov/0610_w03_qp_1.pdf
No. 15 I dont get how water diffuses?I thought water molecules move by osmosis so any help?
Ans: B
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Hello again.
O/n 03 Link :http://www.freeexampapers.us/IGCSE/Biology/CIE/2003%20Nov/0610_w03_qp_1.pdf
No. 15 I dont get how water diffuses?I thought water molecules move by osmosis so any help?
Ans: B
Water evaporates from the mesophyll cells surfaces then diffuses, as vapor, through the intercellular spaces before leaving the leaf through the stomata during TRANSPIRATION. So basically the water first evaporates and then in those spaces u see in the diagram in tht Q well it stays there as water vapor. and when the stomata opens, these water vapors diffuse out through the open stomata. :) hope you got me. :) so yeah the ans is B.
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Hello again.
O/n 03 Link :http://www.freeexampapers.us/IGCSE/Biology/CIE/2003%20Nov/0610_w03_qp_1.pdf
No. 15 I dont get how water diffuses?I thought water molecules move by osmosis so any help?
Ans: B
Water in liq. state move by osmosis, here its evaporates from the spongy mesophyll cells. Water is in gas state (vapor) and all gases diffuse, hence diffusion
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Hey guys please help me I want the answers for 1994-2001 paper 1 bio its there in freeexampapers but its not opening can someone just go there and download it and send it to me on email mdwael@live.com the link is
http://www.freeexampapers.us/IGCSE/Biology/CIE/1993%20-%202003/Answers%20June%201993%20--%202003%20P1,%203,%20&%206.pdf
I will never forget this favour..Its my last exam tommorow, I want it to pass in peace
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The surface waters of the ocean contain a population of microscopic plants (plankton).
Which factor would result in fewer of these plants?
A an increase in the population of microscopic animals
B greater concentration of mineral nutrients
C more light
D warmer ocean water
What's the answer and WHY?
Lol, easy.. ;D its A as microscopic animals will eat these plants.. they get reduced in numbers. :) the other three options will only benefit the plant see? :)
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The surface waters of the ocean contain a population of microscopic plants (plankton).
Which factor would result in fewer of these plants?
A an increase in the population of microscopic animals
B greater concentration of mineral nutrients
C more light
D warmer ocean water
What's the answer and WHY?
A, right? Predators.
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Trickyy.. :/ Please help :)
Is it B?
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The activity of decomposers returns substances to the atmosphere.
Which products of decomposition enter the atmosphere?
A carbon dioxide and nitrogen
B carbon dioxide and water
C oxygen and nitrogen
D oxygen and water
The marking scheme says the answer is B how come its not A?
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The activity of decomposers returns substances to the atmosphere.
Which products of decomposition enter the atmosphere?
A carbon dioxide and nitrogen
B carbon dioxide and water
C oxygen and nitrogen
D oxygen and water
The marking scheme says the answer is B how come its not A?
products of respiration are CO2 and water, I dont see why nitrogen is produced
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Trickyy.. :/ Please help :)
Is it B?
We got the same thinking. I really don't know y. I just guessed it because for these kinda ques. the answer is always awkward, you know what I mean. Which year? What is it given in the ms?
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yeah @ raywin i think it is B too
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The activity of decomposers returns substances to the atmosphere.
Which products of decomposition enter the atmosphere?
A carbon dioxide and nitrogen
B carbon dioxide and water
C oxygen and nitrogen
D oxygen and water
The marking scheme says the answer is B how come its not A?
Nitrogen are only released into the atmosphere by bacteria, NOT decomposers.
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We got the same thinking. I really don't know y. I just guessed it because for these kinda ques. the answer is always awkward, you know what I mean. Which year? What is it given in the ms?
I found these hard Qs posted by some guy on SF.. :S i tried them out, prolly some REALY OLD PAPERS. there was NO ms.. :|
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More Tricky :'(
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GUYS, FIND ALL THE TOUGH QS HERE ;D
https://studentforums.biz/index.php/topic,1612.0.html
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I think I can understand what zarkajordan was thinking... Like if the decomposers breaking down the dead organism, nitrogen is released, but that doesn't enter the ATMOSPHERE, right? It enters the soil? Or the decomposer just eats up the nitrogen or something?
Or is decomposing just a type of food intake and it's breaking that down (like we break down carbs to glucose) for its energy so it's using up the nitrogen and other compounds making up the body of the organism, and releasing CO2 and H20?
Sometimes answers may be all correct, but you should choose the closest one and apparently Water and CO2 are always the products from decomposing. And since they mentioned atmosphere, that means nitrogen isnt there cuz ammonium and nitrates form in the soil by some decomposing bacteria.
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Hey guys is it possible if someone could paste a link of the copy for OCT/NOV 2009 PPR 1 pls!!!!!!! its not opening in FRee exams and even in extreme papers.com
Plssss help
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I found these hard Qs posted by some guy on SF.. :S i tried them out, prolly some REALY OLD PAPERS. there was NO ms.. :|
Why isn't it A? Now I think its A. Its has to be..
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Two samples of a human enzyme were used in an experiment. Before they were used
• sample X was heated to 80 C and then cooled to 37 C
• sample Y was cooled to 0 C and then heated to 37 C.
How will this affect their activity?
A Sample X and sample Y are no longer active.
B Sample X and sample Y will be equally active.
C Sample X will be more active than sample Y.
D Sample Y will be more active than sample X.
Answer, please, and why?
D. This is because if sample X has been heated to 80*c, it would have denatured, it is useless. It wont be active. But, sample Y, however is cooled to 0*c, this doesnt denature it, only slows it. Thus, when heated back to 37*c, it will be more active. So the ans is D. :)
[/quote]
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Hey guys is it possible if someone could paste a link of the copy for OCT/NOV 2009 PPR 1 pls!!!!!!! its not opening in FRee exams and even in extreme papers.com
Plssss help
https://studentforums.biz/index.php/topic,54.msg231725.html#msg231725
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That's what I was thinking at first too, but that's not tricky, lol, so maybe that's not right.
Raywin, maybe you should PM the guy who posted them or something, that way he'll get an alert and send you the answers? lol
He was a guest, i dont think hell be there.. :'(
:D
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Two samples of a human enzyme were used in an experiment. Before they were used
• sample X was heated to 80 C and then cooled to 37 C
• sample Y was cooled to 0 C and then heated to 37 C.
How will this affect their activity?
A Sample X and sample Y are no longer active.
B Sample X and sample Y will be equally active.
C Sample X will be more active than sample Y.
D Sample Y will be more active than sample X.
Answer, please, and why?
Answer is D ofcourse cuz x was heated to 80 degrees so it got denatured, Y jkst got cooled, that doesnt damage it it just makes it temporarly inactive and when its heated to 37 degrees it becomes active
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That's what I was thinking at first too, but that's not tricky, lol, so maybe that's not right.
Raywin, maybe you should PM the guy who posted them or something, that way he'll get an alert and send you the answers? lol
So what it ain't tricky.. Vasoconstriction is the decrease in diameter right? So y not straight forward A BOTH DECREASE ..?
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So what it ain't tricky.. Vasoconstriction is the decrease in diameter right? So y not straight forward A BOTH DECREASE ..?
Hmmm, yeah i guess.. :/ i have neva craved this much for a MS.. :P
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More Tricky :'(
This plz anyone.. :)
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true... it's possible...
what about raywin's other question? that's bugging me too now
Buckle up guys, more coming.. :'(
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This one >:(
:)
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Ello ^^
If there is no trouble, can anyone plaese answer this --> M/J 06 Qs 29, 35, 37 Paper 1.
Thank youu. ;D
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This one >:(
:)
i believe it is C , well it's cuz after the person stops , ur depth of breathing is still deep cuz u have oxygen debt
got it ?
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I believe its C too!!!
This one >:(
:)
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More Tricky :'(
I have a gut feeling that its B.
THESE TYPE OF Q. WONT COME FOR SURE!!!!!!! DON'T PANIC!!
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i believe it is C , well it's cuz after the person stops , ur depth of breathing is still deep cuz u have oxygen debt
got it ?
True, but y cant it be B, cause if u think abt it, after exercise, it takes some time for the breathing to get steady to get to Oxygen debt. and then tht straight line is the time during oxygen debt and then it slowly gets back to normal..
This too can be true ryte? :)
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Not B because hes still exercising as the rate o fheartbeat is INCREASING
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Hey smart guy could u pls download the 2009 OCT/NOV PPR from somewhere!!
I have a gut feeling that its B.
THESE TYPE OF Q. WONT COME FOR SURE!!!!!!! DON'T PANIC!!
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You just got your answer.. So, did you get it?
Lol, so is it A or B? im still in tht confusion. :)
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Ello ^^
If there is no trouble, can anyone plaese answer this --> M/J 06 Qs 29, 35, 37 Paper 1.
Thank youu. ;D
*Ehem*Ehem* Please ::)
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True, but y cant it be B, cause if u think abt it, after exercise, it takes some time for the breathing to get steady to get to Oxygen debt. and then tht straight line is the time during oxygen debt and then it slowly gets back to normal..
This too can be true ryte? :)
look it can't be B, cuz after b the curve is a bit increasin and then it stays the same at the same point .... it's gotta be C , i just solved it with my tutor a few hours ago ...so trust me it's C ;)
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Hey smart guy could u pls download the 2009 OCT/NOV PPR from somewhere!!
I did post the link..
https://studentforums.biz/index.php/topic,54.msg231725.html#msg231725
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*Ehem*Ehem* Please ::)
Working.. :)
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look it can't be B, cuz after b the curve is a bit increasin and then it stays the same at the same point .... it's gotta be C , i just solved it with my tutor a few hours ago ...so trust me it's C ;)
Oh well in tht case, its C.. ;D
Thanks a lot :D
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*Ehem*Ehem* Please ::)
srry but my brain can't function anymore cuz of me sleepin really late yesterday , havin two exam in a row so i'm goin to bed to rest *snores*...
i hope VIN helps ya ;)
np raywin :D
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Working.. :)
Thank you.
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srry but my brain can't function anymore cuz of me sleepin really late yesterday , havin two exam in a row so i'm goin to bed to rest *snores*...
i hope VIN helps ya ;)
np raywin :D
Its okaay
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srry but my brain can't function anymore cuz of me sleepin really late yesterday , havin two exam in a row so i'm goin to bed to rest *snores*...
i hope VIN helps ya ;)
np raywin :D
Good luck with them.. :)
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Its okaay
thx alot mates ;) ......Salam *snores* :P
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;D heres another, not tricky but fresh fruits give us wht? ???
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I did post the link..
Thanks a lot!!
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its C....
ur heart beat can not continuously be increasing during excercise because otherwise tht wud be dangerous...so it becomes constant after some time..then when u stop it slowly starts decreasing to normal ...
therfore the answer is definitely a C :)
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;D heres another, not tricky but fresh fruits give us wht? ???
The answer is C.
I remember from class, that pirates and sailors usually get scurvy because they eat all their fruit at once and at the end they have no fruit, so they get it. I think it gives vitamin C.
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The answer is C.
I remember from class, that pirates and sailors usually get scurvy because they eat all their fruit at once and at the end they have no fruit, so they get it. I think it gives vitamin C.
I meant D!!
Haha, oopsy my baad! ::)
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Scurvy, Choice D. Fresh fruits = citrus fruits = vitamin C = deficiency disease of not having that is scurvy. That's the only choice that makes sense.
The oxygen debt one, I think I've solved it before? Or something similar to it. It's C, FOR SURE.
The answer is C.
I remember from class, that pirates and sailors usually get scurvy because they eat all their fruit at once and at the end they have no fruit, so they get it. I think it gives vitamin C.
its C....
ur heart beat can not continuously be increasing during excercise because otherwise tht wud be dangerous...so it becomes constant after some time..then when u stop it slowly starts decreasing to normal ...
therfore the answer is definitely a C
THANKS A LOT. ;D
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I meant D!!
Haha, oopsy my baad! ::)
Hahaha, its k and good way to remember tht pirates thingi.. ;)
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THANKS A LOT. ;D
Your welcome ;)
Anytime ;D
But in my answer i meant D, not C, sorry about that.
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Hahaha, its k and good way to remember tht pirates thingi.. ;)
I know, thats why i still remember! ;D
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@Raywin: I've downloaded these before, are you just going through them all randomly?
ALSO, what happened to that X-Y-Z plant tropisms question?? Did you all figure out an answer?
Yeah, randomly solving to myself and if in doubt posting it here.. ;D
and O.O nope no answer yet.
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More Tricky :'(
Guys, any one know the ans to this? ???
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Please name all the types of cells in plants that have chloroplasts? (I know palisade and spongy mesophyll do, and guard cells have a few. Are there any others though?)
Relatively how many does each have? Like on a scale of 10, palisade would have 10, spongy would have maybe 5? and Guard cells would have like 2 or 3?
:/ hmmm i think thts all. and tht scale also suits it.. :) u got it. :)
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Ello ^^
If there is no trouble, can anyone plaese answer this --> M/J 06 Qs 29, 35, 37 Paper 1.
Thank youu. ;D
Pretty pleasse! :-*
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Guys, any one know the ans to this? ???
I'm pretty sure it's B. The jelly allows auxin to pass through the tip. And the foil prevents it. Though it'd be better if someone more experienced could confirm this :D
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I'm pretty sure it's B. The jelly allows auxin to pass through the tip. And the foil prevents it. Though it'd be better if someone more experienced could confirm this :D
Thanks, can anyone confirm this.. ;D
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that sounded pretty experienced to me... lol
anyone think we'll get as hard a question as this tomorrow???
what is agar jelly specifically? how does foil prevent it? how does the jelly allow it?
I have the same Qs.. :D all i noe is tht agar jelly solidifies.. :/ but im not sure how it implys to this Q.
And i doubt well get this hard Qs tomoz, but hey who wants to take the risks? ;)
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*Ehem*Ehem* Please ::)
REALLY SORRY FOR THE DELAY I was having my dinner... :-[
29) Difficult to explain .. tried my best..Drawing a punett square would make life easier.. Q. says n.blindness is caused by a dominant allele. If we take them to be N-dominant and n-recessive
then..attached
35) Decomposers always produce CO2 and H2O while decomposing and NOT N2
37) B,
opt. A belongs to only to water cycle
opt. C is neither
opt.D is again water cycle
(http://www.indiana.edu/~geol105b/images/gaia_chapter_8/carbon%20cycle-2.gif)
EDIT:: Image slightly modified.
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Pretty pleasse! :-*
SORRY check my post^^ https://studentforums.biz/index.php/topic,1411.msg259616.html#msg259616
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that sounded pretty experienced to me... lol
anyone think we'll get as hard a question as this tomorrow???
what is agar jelly specifically? how does foil prevent it? how does the jelly allow it?
Haha, thanks :)
I just know that agar jelly is used to grow plants artificially in laboratories, so it can absorb chemical substances. That's how it allows the auxin to pass through. Foil is pretty much impermeable, so I assume it wouldn't let auxin get through.
You could check this out if you want a more detailed description though:
http://en.wikipedia.org/wiki/Agar (http://en.wikipedia.org/wiki/Agar)
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Haha, thanks :)
I just know that agar jelly is used to grow plants artificially in laboratories, so it can absorb chemical substances. That's how it allows the auxin to pass through. Foil is pretty much impermeable, so I assume it wouldn't let auxin get through.
You could check this out if you want a more detailed description though:
http://en.wikipedia.org/wiki/Agar (http://en.wikipedia.org/wiki/Agar)
Thx ;) +rep
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Hi! Could someone please explain to me number 14 of june 2008?
Here's the link:
http://www.freeexampapers.us/IGCSE/Biology/CIE/2008%20Jun/0610_s08_qp_1.pdf
The answer is B
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Hi! Could someone please explain to me number 14 of june 2008?
Here's the link:
http://www.freeexampapers.us/IGCSE/Biology/CIE/2008%20Jun/0610_s08_qp_1.pdf
The answer is B
Its B. For the blood (transport of o2) iron is needed. So just look in the graph of Fe and choose the food with the highest content of iron, eggs!! :)
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Hi! Could someone please explain to me number 14 of june 2008?
Here's the link:
http://www.freeexampapers.us/IGCSE/Biology/CIE/2008%20Jun/0610_s08_qp_1.pdf
The answer is B
its because iron is needed to make haemoglobin which is needed to transport oxygen.
since egg is the richest in iron, its the most suitable answer! :D
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REALLY SORRY FOR THE DELAY I was having my dinner... :-[
29) Difficult to explain .. tried my best..Drawing a punett square would make life easier.. Q. says n.blindness is caused by a dominant allel. If we take them to be N-dominant and n-recessive
then..attached
35) Decomposers always produce CO2 and H2O while decomposing and NOT N2
37) B,
opt. A belongs to only to water cycle
opt. C is neither
opt.D is again water cycle
(http://www.indiana.edu/~geol105b/images/gaia_chapter_8/carbon%20cycle-2.gif)
Thank you, thank you, thank you, dude you are AWESOME! :-*
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Thanks Raywin and SNA!!
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Thanks Raywin and SNA!!
Anytime.. :) glad to help. ;D
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Thank you, thank you, thank you, dude you are AWESOME! :-*
Ha ha glad you got it :)
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If a question asks you for the best measurement to determine growth, is it dry mass? Even though you'd have to kill the organism?
(Or, this just occurred to me, does it depend on whether the organism in question is a human or a plant?)
Its dry mass. :)
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Could someone someone temme which is the correct answer please , it has always confused me??
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What are the common enzymes tested on Paper 1 and the pH's of each...?
If anyone can suggest a couple names????
Thanks in advance :)
Amylase (salivary and pancreatic) both neutral = starch to maltose
Maltase (from pancreas) alkaline = maltose to glucose
Lipase (from pancreas) alkaline = lipids(fats) to fatty acids and glycerol
Protease (in stomach) acidic = proteins to amino acids
Im sure u need to know all these. :)
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What are the common enzymes tested on Paper 1 and the pH's of each...?
If anyone can suggest a couple names????
Thanks in advance :)
https://studentforums.biz/index.php/topic,7967.msg211170.html#msg211170
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Could someone someone temme which is the correct answer please , it has always confused me??
Its D. :)
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Thanks Raywin :)
It makes sense XD
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Thanks Raywin :)
It makes sense XD
Lol, i just stated the answer.. :P anywyas np.
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I swear I love you guys so much. I'm +repping you both, you guys SO deserve it!!!!!!!!!!!!!!!!!!!
Hahaha, np and thanks ;D
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Could someone someone temme which is the correct answer please , it has always confused me??
D. pls. dont quote this :P good pic, eh? If someone annoyed, I'll reduce the size.
(http://faculty.ksu.edu.sa/75719/Pictures%20Library/Cardiovascular%20system/Direction%20of%20blood%20flow%20through%20the%20heart.jpg)
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D.
(http://faculty.ksu.edu.sa/75719/Pictures%20Library/Cardiovascular%20system/Direction%20of%20blood%20flow%20through%20the%20heart.jpg)
Woaaah, cool heart! ;)
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How are both water and land plants affected by each of the following:
1) pesticides
2) herbicides
3) fertilizers
4) anything else the stupid examiners test us on related to this question >:(
These questions ALWAYS confuse me :(
Again, thank you in advance
Pesticides kill the pests (insects) tht ummm annoy the plant :P.
Herbicides kills the unwanted plants like weeds etc.
Fertilizers helps plants grow (they contain NPK - Nitrogen, Phosphorous and Potassium which are essential for plant growth )
;D
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Pesticides kill the pests (insects) tht ummm annoy the plant :P.
Herbicides kills the unwanted plants like weeds etc.
Fertilizers helps plants grow (they contain NPK - Nitrogen, Phosphorous and Potassium which are essential for plant growth )
;D
in addition to that, fertilizers cause aquatic plants to grow rapidly at first (algal bloom)
then cause them to die. but not sure for herbicides and pesticides though. sorry :(
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Hardest past paper you've ever done before the year 2004?
Lol tht thing I downloaded from SF today.. :P everything else was pretty much fine.. :)
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Thanks Raywin and SNA, I appreciate the efforts!!
I'm sure the herbicides and pesticides would have the same effect in water as on land? Can someone confirm this, and thanks again!
Hmm, fertilizers would have but im not sure about herbicides and pesticides.. :/
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Guys, imma go off now.. :) its late night here and i need to catch up on some sleep.. ;D so good luck for everyone doing bio p1 tomoz!! ;D
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Could someone someone temme which is the correct answer please , it has always confused me??
D, S->R->P->Q. Blood from muscles in leg flow through vena cava to right aorta then left ventricle, then goes to pulonary artery to lungs (not shown) then arrives by pulmonary vein then into left aorta then left ventricle.
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Thanks Raywin and SNA, I appreciate the efforts!!
I'm sure the herbicides and pesticides would have the same effect in water as on land? Can someone confirm this, and thanks again!
hey gud news! i checked the exam syllabus, only need to know:
-describe the importance of:
• nitrate ions for protein synthesis
• magnesium ions for chlorophyll synthesis
- describe the uses, and the dangers of overuse,
of nitrogen fertilisers
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I'd appreciate it if someone could give me answers for he four questions attached pleaseeee :)
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http://www.freeexampapers.us/IGCSE/Biology/CIE/2005%20Nov/0610_w05_qp_1.pdf
Q 1 I dnt get how excretion is shown in this diagram(plants) any help ?
Thanks in advance ;)
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I'd appreciate it if someone could give me answers for he four questions attached pleaseeee :)
6. B
7. A ( not sure )
10. B
11. A
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I'd appreciate it if someone could give me answers for he four questions attached pleaseeee :)
B
A
B
B (can you explain how is it A?)
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B
A
B
B (can you explain how is it A?)
u're right!!!!cheese i should have checked!
im sooo sorry!!!i tot it was artery...so stupid of me...
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http://www.freeexampapers.us/IGCSE/Biology/CIE/2005%20Nov/0610_w05_qp_1.pdf
Q 1 I dnt get how excretion is shown in this diagram(plants) any help ?
Thanks in advance ;)
aangel42 is right ;)
Flower > Fruit (reproduction), Seedling to Plant (growth)
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u're right!!!!cheese i should have checked!
im sooo sorry!!!i tot it was artery...
Its absolutely fine ;)
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That's because it's not?
The right answer is B, only growth and reproduction are shown by the diagram.
Please don't get confused by the characteristics of living things - these are easy points, so review this, since I think EVERY paper I've done has had a question about it and most likely, we'll have such a question tomorrow too.
Good luck!
Soorry i dnt get reproduction in the diagram is this asexual thts why??????
Thanks for the tip :)
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You're right about all of them, including the last one.
The first one confused me though :-\ ???
look at the arrows..
A and C- not possible as blood as blood cannot directly go to the lungs
D- not possible for blood to travel from lung to the rest of the body..
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Soorry i dnt get reproduction in the diagram is this asexual thts why??????
Thanks for the tip :)
Reproduction :: Flower to fruit (recollect pollination), nothing to do with asexual.
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Thanks Vin & SNA so veryyyy much :D
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what does "xylem conducts" mean?
oh and what are the inorganic compounds that are transported by xylem??
Please and thank you!
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Reproduction :: Flower to fruit (recollect pollination), nothing to do with asexual.
True, true so sorry to be wasting your time :(
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You're right about all of them, including the last one.
The first one confused me though :-\ ???
deoxygenated blood from cells goes into heart. heart pumps the deoxygenated blood into the lungs to get oxygen. from the lungs ( now oxygenated blood) blood goes into heart again and gets pumped to the rest of the body. then the cirulation starts again.
double circulation = blood flows through the heart twice
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what does "xylem conducts" mean?
Basically "xylem conducts water", that's what it means ;)
oh and what are the inorganic compounds that are transported by xylem??
Please and thank you!
Sodium ions, Potassium ion, nitrate salts, nitrites salts, Ca and Mg ions .. anything else? (all dissolved in water)
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And these too if u ppl please?
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Basically "xylem conducts water", that's what it means ;)
ah yes makes sense :P thank youu!
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True, true so sorry to be wasting your time :(
NO problem at all! ;)
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Basically "xylem conducts water", that's what it means ;)
Sodium ions, Potassium ion, nitrate salts, nitrites salts, Ca and Mg ions .. anything else? (all dissolved in water)
nope, thats plenty thanks so much.
you spend so much time helping out here i wonder when YOU actually get time to study and solve? :P
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And these too if u ppl please?
D
B
B
want explanation?
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A woman is most fertile when she ovulates. I'll fetch you a pic.
(http://www.medindia.net/patients/patientinfo/Images/menstrual-cycle.gif)
(http://www.maybe-baby.com/gallery/images/1144828120Cycle.jpg)
^^ Should help :) (Right click> View image)
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Please can someone explain these doubts.
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Okay, this is really frustrating my textbook (Mary Jones) and study guide (Dave Hayward) DO NOT cover fertility in women in depth. I'm getting all the menstrual cycle questions/related questions wrong.
Someone please help with M/J 03 Q27 (attached) and why it's not D, because doesn't the egg take a couple days to pass down?
Also about the lining shedding and thickening and stuff, what are the days this happens? I think I asked before, and Vin said that ovulation happens around day 14?
lol the egg doesn't exactly last "a couple of days." It can only survive for about 24 hours after being released. And sperm can survive inside the female for about 2-3 days. So there's hardly a period of 4 days when fertilisation can occur. Thus it must be C (remember fertilisation should be around ovulation). Secondly, the time period for D is too large. Thirdly, the sperm don't really fertilize an ovum in uterus. They do it when the egg is moving down and is in the oviducts. Thus it must be C.
Do you have IGCSE Biology by DG Mackean?? (the book of that study guide?) it covers this aspect in a lot of detail...
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Well the first is D...
Please can someone explain. I thought photosynthesis (plant nutrition) absorbs carbon dioxide and gives off oxygen. Why respiration?
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Okay, this is really frustrating my textbook (Mary Jones) and study guide (Dave Hayward) DO NOT cover fertility in women in depth. I'm getting all the menstrual cycle questions/related questions wrong.
Someone please help with M/J 03 Q27 (attached) and why it's not D, because doesn't the egg take a couple days to pass down?
Also about the lining shedding and thickening and stuff, what are the days this happens? I think I asked before, and Vin said that ovulation happens around day 14?
it is C as that when ovulation (release of an ovum ) occurs thus, the female is most fertile. for D, this is when the lining thicken, in preparation for implantation to occur if fertilisation takes place. if fertilisation does not happen, the thickening uterus wall will break down causing menstruation. hope this helps!^^
(http://www.coachr.org/growth7.jpg).
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Please can someone explain. I thought photosynthesis (plant nutrition) absorbs carbon dioxide and gives off oxygen. Why respiration?
without presence of sunlight,(usually at night) plant respire ,releasing co2.
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Well the first is D...
And the third is B?
Why B? And the second is a bit weird.
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without presence of sunlight,(usually at night) plant respire ,releasing co2.
Correction: plants always respire!!!
It involves the same equation as for humans (aerobic respiration = oxygen in, CO2 out)
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Please can someone explain. I thought photosynthesis (plant nutrition) absorbs carbon dioxide and gives off oxygen. Why respiration?
Respiration uses O2 and gives off CO2, these.
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Heyy can anyone please help me out with June 09 Q 3)
How cum it's not B and it's D...doesnt the plant have just four stamen ..UGHHH... ???
I cant manage more than 37 :(
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Why B? And the second is a bit weird.
Yeah, exactly, I don't get the second at all, to be quite honest.
Ok, so I think it's B, because well major clue, is that heating is only occurring at A and B, so it has to be either one. When conducting a starch test, you must first boil the leaf in water to kill it (= liquid A is water) and then in alcohol, to dissolve the green chlorophyll so that the black coloring from when you put the iodine doesn't interfere and mix the colors up.
Another huge clue is the presence of the test tube, ethanol is a flammable liquid, so even if you have no idea about the starch test stages, you can just narrow it down to A and B, and guess with B since a test tube is present, so there's a higher chance that would be the answer.
Can anyone confirm this? And answer the second one?
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Please can someone explain. I thought photosynthesis (plant nutrition) absorbs carbon dioxide and gives off oxygen. Why respiration?
I think you're confusing it. Look it says which process leads DIRECTLY to the exchange of gases indicated. During the night, plants don't make oxygen from photosynthesis so they have to absorb it. And since they aren't photosynthesising, they release it carbon dioxide directly. During the part of the day with bright sunlight, the oxygen is still produced but its actually a lot more than necessary and released. Carbon dioxide is also made but its a lot less. So the plant has to absorb it from the surroundings...
Secondly, in that question about seeds, its wind for seed 2 cause look at it. They have a large surface area to increase air resistance..
and the other is mammal for attaching to it (I've never seen birds with seeds on em :D.)
Thirdly, that question about the leaf, alcohol (common reference to ethanol) is B. Just recall the process of testing a leaf for starch. First, its boiled to make it permeable, then heated with ethanol (using a water bath since ethanol is flammable) to dissolve chlorophyll then washed with water then iodine is added...
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Please can someone explain these doubts.
1. D, Respiration uses O2 and gives off CO2
2. B, Spiked fruit 1 sticks to mammal fur, fruit 2 feathered and has large surface area so modified to be dispersed by wind
3.B, alcohols are always heated in a water bath to avoid combustion when in direct touch with flame.
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1. D, Respiration uses O2 and gives off CO2
2. B, Spiked fruit 1 sticks to mammal fur, fruit 2 feathered and has large surface area so modified to be dispersed by wind
3.B, alcohols are always heated in a water bath to avoid combustion when in direct touch with flame.
LOL, I thought the fruits were carrots and potatoes!
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LOL, I thought the fruits were carrots and potatoes!
Fruit is anything formed by fertilization that produces seeds in the ovary in flowering plants. That also makes tomato fruits !!:D.
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Correction: plants always respire!!!
It involves the same equation as for humans (aerobic respiration = oxygen in, CO2 out)
during daylight, plants photosynthesis as well as respire, so that all co2 produced by respiration is used up by photosynthesis. at the same time, all oxygen needed by respiration is provided by photosynthesis. when in dark, plants do not photosynthesis. thus the rate of respiration is faster than photosynthesis,thus releasing co2 gas.
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Heyy can anyone please help me out with June 09 Q 3)
How cum it's not B and it's D...doesnt the plant have just four stamen ..UGHHH... ???
I cant manage more than 37 :(
(http://www.sbs.utexas.edu/bio406d/images/pics/poa/Arundo%20donax%20leaf5.jpg)
^^Monocot leaf- parallel veins
(http://homepage.smc.edu/hodson_kent/plant_growth/Angiosperms/tissues/dicot_leaf.jpg)
^^Dicot Leaf- fibered/branched veins
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Another doubt, please help. I think it's been answered before, but why is the silver thing stopping it? it's only thin layer, so surely auxins are still exposed on shoot tip.
I mean metal, not silver! ;P
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Another doubt, please help. I think it's been answered before, but why is the silver thing stopping it? it's only thin layer, so surely auxins are still exposed on shoot tip.
I mean metal, not silver! ;P
Don't really break your head because its not it the syllabus! ;)
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Don't really break your head because its not it the syllabus! ;)
*phew* I couldn't answer it. :P
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Another doubt, please help. I think it's been answered before, but why is the silver thing stopping it? it's only thin layer, so surely auxins are still exposed on shoot tip.
I mean metal, not silver! ;P
First thing that I can't really get is that have they managed to cut the shoot into two and then placed agar and metal or have they made a hole and passed a shoot through it lol :D.
If they've cut it, they I think the one with agar jelly and the untouched shoot should show tropism. How??? I don't feel right choosing metal lol :D...
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First thing that I can't really get is that have they managed to cut the shoot into two and then placed agar and metal or have they made a hole and passed a shoot through it lol :D.
If they've cut it, they I think the one with agar jelly and the untouched shoot should show tropism. How??? I don't feel right choosing metal lol :D...
LOL ... This is what I can't understand too. Anyway, apparently the explanation is :: The sugar agar allows the auxin to pass through as it is organic and the metal doesn't.
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Guys just one thing, in the circulatory system what is an artery??? I mean an organ, tissue etc. And is blood actually a tissue here??? (LOL my understanding of tissues is limited to colony of cells :D)...
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LOL ... This is what I can't understand too. Anyway, apparently the explanation is :: The sugar agar allows the auxin to pass through as it is organic and the metal doesn't.
Most probably!!
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Umm, M/J 2000, P1, Q 27.
How is the answer D?
Shouldn't it be C, because the foliage leaves have begun to develop, and as soon as they do, photosynthesis starts, thus increasing the mass.
Though there is also a possibility that the production and usage is at equilibrium, because they plant is still growing, so the is making use of the resources?
But, point is, the increase should start as leaves have formed, and that is C.
???
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Guys just one thing, in the circulatory system what is an artery??? I mean an organ, tissue etc. And is blood actually a tissue here??? (LOL my understanding of tissues is limited to colony of cells :D)...
Arteries and veins are BLOOD VESSELS
Blood cannot be a tissue, though it may have RBCs or WBCs, collection if cells as you say.. they don't really "join up" to do specific tasks. Let's just say the blood is a mixture of cells, ions etc. etc.
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Arteries and veins are BLOOD VESSELS
Blood cannot be a tissue, though it may have RBCs or WBCs, collection if cells as you say.. they don't really "join up" to do specific tasks. Let's just say the blood is a mixture of cells, ions etc. etc.
So... an artery is a tissue? Or an organ?
Tissue, right?
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Umm, M/J 2000, P1, Q 27.
How is the answer D?
Shouldn't it be C, because the foliage leaves have begun to develop, and as soon as they do, photosynthesis starts, thus increasing the mass.
Though there is also a possibility that the production and usage is at equilibrium, because they plant is still growing, so the is making use of the resources?
But, point is, the increase should start as leaves have formed, and that is C.
???
Can you like, post the paper/question/which page is it from the big 350 paged pdf? Would be great help.. :)
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Don't really break your head because its not it the syllabus! ;)
What? I thought there was stuff about auxin?
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Arteries and veins are BLOOD VESSELS
Blood cannot be a tissue, though it may have RBCs or WBCs, collection if cells as you say.. they don't really "join up" to do specific tasks. Let's just say the blood is a mixture of cells, ions etc. etc.
You seem right VIN but we had that dumb question in our mocks. It was from GCE and it called blood to be a tissue I think. Not really sure of the year. Anyway, screw it. GCE doesn't count :D :D. But about an artery, isn't it a tissue?? Cause I came across a question in MJ 00 that called it an organ. (the mark scheme for those years is just downright nuts...). Just 3 pm tomorrow and after that no force other then that of God can force me to study for at least 6 weeks. Fifa 2010 here I come!!!!!
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You seem right VIN but we had that dumb question in our mocks. It was from GCE and it called blood to be a tissue I think. Not really sure of the year. Anyway, screw it. GCE doesn't count :D :D. But about an artery, isn't it a tissue?? Cause I came across a question in MJ 00 that called it an organ. (the mark scheme for those years is just downright nuts...). Just 3 pm tomorrow and after that no force other then that of God can force me to study for at least 6 weeks. Fifa 2010 here I come!!!!!
I play FIFA10 as well, it' so fun.
By the way, past paper said artery is organ?
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D
B
B
want explanation?
Yes please for 7 & 8 if possible :)
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So... an artery is a tissue? Or an organ?
Tissue, right?
Um, I'm not sure because they are different compositions of elastic and muscle tissue, so I don't know if they are called tissue alone. They are usually referred to as blood vessels. There are different arteries with different compositions of elastic and muscle tissue, like pulmonary artery and a normal artery (I don't know any other arteries).
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Arteries and veins are BLOOD VESSELS
Blood cannot be a tissue, though it may have RBCs or WBCs, collection if cells as you say.. they don't really "join up" to do specific tasks. Let's just say the blood is a mixture of cells, ions etc. etc.
then,can we say blood to be a system?
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X and Z?
Or maybe the metal foil would reflect the light or mess it up or something, so only X?
Maybe the agar jelly is too heavy? Or maybe it makes no difference and Y too?
I DON'T KNOW :'( :'( :'( :'( :'( :'(
X, Y Z
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Yes please for 7 & 8 if possible :)
Got 4 right? Always more auxin is on the darker side.
7th ::::
Don't really break your head because its not it the syllabus! ;)
LOL ... This is what I can't understand too. Anyway, apparently the explanation is :: The sugar agar allows the auxin to pass through as it is organic and the metal doesn't.
OK 8 ) Auxin always go away from light and multiply cells in that region. This results in the bending of the plant due to excessive growth.
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then,can we say blood to be a system?
OK you are confusing me and yourself :P
Circulatory System
Arteries and veins : Blood Vessels (which carry blood), they are simply combination of muscles and tissues.
Blood : Medium of transportation throughout the body.
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Can you like, post the paper/question/which page is it from the big 350 paged pdf? Would be great help.. :)
M/J 2000 question 27, page 208/351.
I don't get it either.
It's such a vaguely worded question for which ANY of the choices could be the right answer.
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M/J 2000 question 27, page 208/351.
I don't get it either.
It's such a vaguely worded question for which ANY of the choices could be the right answer.
What is the answer? Is it D?
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What is the answer? Is it D?
Yes but why!! It should be C in my view. I mean the folliage leaves photosynthesise don't they???
Anyway,
Well after some searching, I've come across this...
http://wiki.answers.com/Q/Is_blood_concidered_a_connective_type_tissue
the only thing I get is that blood is some sort of a tissue. Plus they're calling artery to be the same type (connective?) tissue. AHHHH!!!! I hate Bio!!! Why did I choose this subject!!!!
@ Ivo YOU play Fifa 2010??? Surprising. I suppose you're a girl (guessing from you avatar). Not many girls I know like it lol. My sister never plays it with me cause I beat here with scores like 3-0 or 5-0 loool :D...
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does anyone have markscheme for bio unit 2 speciman papers ! fast reply please!
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um... oct 2009 q 18
y is it B?
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Yes but why!! It should be C in my view. I mean the folliage leaves photosynthesise don't they???
Anyway,
Well after some searching, I've come across this...
http://wiki.answers.com/Q/Is_blood_concidered_a_connective_type_tissue
the only thing I get is that blood is some sort of a tissue. Plus they're calling artery to be the same type (connective?) tissue. AHHHH!!!! I hate Bio!!! Why did I choose this subject!!!!
@ Ivo YOU play Fifa 2010??? Surprising. I suppose you're a girl (guessing from you avatar). Not many girls I know like it lol. My sister never plays it with me cause I beat here with scores like 3-0 or 5-0 loool :D...
The leaves begin to photosynthesis. There is a greater increase in mass in stage four, in all others the stored food (starch) is used up so decrease in mass.
That is way above our level. I think we should stick to our syllabus.
I bought FIFA 2010 long time ago, but never tried it. But imma play it too soon ;D
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um... oct 2009 q 18
y is it B?
can you please state the question as i cant open 2009 papers on fep. :D
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OK you are confusing me and yourself :P
Circulatory System
Arteries and veins : Blood Vessels (which carry blood), they are simply combination of muscles and tissues.
Blood : Medium of transportation throughout the body.
sorry....cheese! i hope they don't ask any questions like this tomorrow!
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Hello once again .
Why is the answer B in O/N 09 q 5 p 12??
Remind me please of insect's characteristics?
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um... oct 2009 q 18
y is it B?
A- The person is resting as there is no change in the breathing rate.
B- He is exercising as increase in breathing rate.
C-HE has stopped exercising at this point so the body is coping up with the oxygen dept created therefore graph parallel to x-axis.
D- Recovered from O2 dept so rate slowly decreasing until original rate.
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A- The person is resting as there is no change in the breathing rate.
B- He is exercising as increase in breathing rate.
C-HE has stopped exercising at this point so the body is coping up with the oxygen dept created therefore graph parallel to x-axis.
D- Recovered from O2 dept so rate slowly decreasing until original rate.
He aint talking about this varient so check 12 and pls answer :)
Oh & for the one u answered the answer is A look closely thts when the person started excersing as ur heart beat does not instantly or steeply on the graph increase but need time .
Hope I've been beneficial :D
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can you please state the question as i cant open 2009 papers on fep. :D
here q18 plz
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Hello once again .
Why is the answer B in O/N 09 q 5 p 12??
Remind me please of insect's characteristics?
Has 3 pairs of legs. Its a mosquito.
Insects - 3 pairs of (jointed) legs, body divided into head-thorax-abdomen, 2 pair of wings/antennae, Eg-housefly, beetle cockroach
Arachnids- 4 pairs of (jointed) legs, head and thorax fused- abdomen, lack wings and antennae, compound eyes Eg, Spider, scorpion
Crustacea- 1/2 pairs of legs, body divided into head-thorax-abdomen, chitinous exoskeleton. Eg. Crabs, lobsters.
Myriapods-Segmented body, many legs(usually 2 per segment), Obvi. not divided into head-thorax-abdomen. Eg. Centipede, millipede
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He aint talking about this varient so check 12 and pls answer :)
Oh & for the one u answered the answer is A look closely thts when the person started excersing as ur heart beat does not instantly or steeply on the graph increase but need time .
Hope I've been beneficial :D
Oh okay, I was wondering why the answer was B, thanks :)
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Has 3 pairs of legs. Its a mosquito.
Insects - 3 pairs of (jointed) legs, body divided into head-thorax-abdomen, 2 pair of wings/antennae, Eg-housefly, beetle cockroach
Arachnids- 4 pairs of (jointed) legs, head and thorax fused- abdomen, lack wings and antennae, compound eyes Eg, Spider, scorpion
Crustacea- 1/2 pairs of legs, body divided into head-thorax-abdomen, chitinous exoskeleton. Eg. Crabs, lobsters
Myriapods-Segmented body, many legs(usually 2 per segment), Obvi. not divided into head-thorax-abdomen. Eg. Centipede, millipede
LOADS OF THANKS 4 THE EXTRAS :D
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here q18 plz
i think the answer is B.this is how i think would be the reason. for P, the liquid moves to the left as soda lime adsorbs the co2 which lowers air pressure in test tube. thus, higher air pressure outside tube pushes liquid towards the test tube. for Q,air pressure inside test tube and outside is the same,so the liquid stays at the same place.the glass beads did not effect the experiment.
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Which one and why plz ???
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i think the answer is B.this is how i think would be the reason. for P, the liquid moves to the left as soda lime adsorbs the co2 which lowers air pressure in test tube. thus, higher air pressure outside tube pushes liquid towards the test tube. for Q,air pressure inside test tube and outside is the same,so the liquid stays at the same place.the glass beads did not effect the experiment.
Thanks alot!! gud luck 4 bio
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i think D
because xylem is a hollow tube and doesnt absorb anything and it cant contract either
it is dead
and it is used for support so.. D
tho i may be wrong
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i think the answer is B.this is how i think would be the reason. for P, the liquid moves to the left as soda lime adsorbs the co2 which lowers air pressure in test tube. thus, higher air pressure outside tube pushes liquid towards the test tube. for Q,air pressure inside test tube and outside is the same,so the liquid stays at the same place.the glass beads did not effect the experiment.
Yes & No for the first part True but 4 the 2nd Co2 is released but not absorbed u would assume that it would move to the right but NO because dnt 4get oxygen is absorbed :)
Hope tht helped!
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Which one and why plz ???
conduction and support. conduction is like transport of water and mineral ions.
support is because, w/o water the plant will wilt. with water, the plant is like fresh and straight etc
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Yes & No for the first part True but 4 the 2nd Co2 is released but not absorbed u would assume that it would move to the right but NO because dnt 4get oxygen is absorbed :)
Hope tht helped!
;D that was what i meant by air pressure in test tube stays the same as carbon dioxide released but O2 absorbed. but you explained it better. thank you! ;)
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Ok Thanks kstina and SNA, :D
i was like absorbtion :P
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Ok Thanks kstina and SNA, :D
i was like absorbtion :P
no prob ;)
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Yes & No for the first part True but 4 the 2nd Co2 is released but not absorbed u would assume that it would move to the right but NO because dnt 4get oxygen is absorbed :)
Hope tht helped!
There is no significant role of the beads..right?
-
There is no significant role of the beads..right?
NEW NAME ::)
COOL 8)
-
There is no significant role of the beads..right?
nope..just to confuse or just to make the experiment look more pretty..haha.. :P
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Ok Thanks kstina and SNA, :D
i was like absorbtion :P
no prob! :D
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nope..just to confuse or just to make the experiment look more pretty..haha.. :P
Ha ha :D right, experiment looks pretty .. XD
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NEW NAME ::)
COOL 8)
thanks ;D
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;D that was what i meant by air pressure in test tube stays the same as carbon dioxide released but O2 absorbed. but you explained it better. thank you! ;)
Hah sorry & thanks i didnt quite get it but nw i do :)
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There is no significant role of the beads..right?
Nop :)
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Could someone please help me check my answers here are the questions sorry they are many at once hope they are clear in attachment ??
-
Umm may june 09 q9 could someone tell me briefly why is it A ?
Link:www.freeexampapers.us/IGCSE/Biology/CIE/2009%20Jun/0610_s09_qp_1.pdf
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Could someone please help me check my answers here are the questions sorry they are many at once hope they are clear in attachment ??
1. D
2. A
3. A
4. B ( not sure )
5. D
Hope it helped!
-
1. D
2. A
3. A
4. B ( not sure )
5. D
Hope it helped!
Damn straight it helped :)
Thanks hope someone else could continue !
-
Umm may june 09 q9 could someone tell me briefly why is it A ?
Link:www.freeexampapers.us/IGCSE/Biology/CIE/2009%20Jun/0610_s09_qp_1.pdf
water leaves the vacuole by osmosis. Vacuole shrinks,the cytoplasm and cell membrane are pulled away from cell wall.cell is plasmolysed.
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Damn straight it helped :)
Thanks hope someone else could continue !
haha..im gonna be here all day,well if my mom doesnt force me to sleep..
im too fired up to even sleep.tomorrow is my last paper!
:D
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water leaves the vacuole by osmosis. Vacuole shrinks,the cytoplasm and cell membrane are pulled away from cell wall.cell is plasmolysed.
UR BRILLIANT :D
+Rep 4 u now :)
-
Could someone please help me check my answers here are the questions sorry they are many at once hope they are clear in attachment ??
1.C
2.A
3.A
4.B
5.D
6.D
7.D
8.B
9.B (not sure-sh*t i forgot)
10.B
11.A
12.B
^^someone pls. crosscheck..
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haha..im gonna be here all day,well if my mom doesnt force me to sleep..
im too fired up to even sleep.tomorrow is my last paper!
:D
Same here but i have to so imana go .
Sleep well u will need it :)
Byee !
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Same here but i have to so imana go .
Sleep well u will need it :)
Byee !
HAhahaha same here!!! Last paper tomorrow!!!!! I'm no fan of CIE but at least they managed to wrap up all our papers before the world cup!!!!
-
By the way can human excrete carbon dioxide? What else can they excrete then?
-
1.C
2.A
3.A
4.B
5.D
6.D
7.D
8.B
9.B (not sure-sh*t i forgot)
10.B
11.A
12.B
^^someone pls. crosscheck..
I think so but one i thoiught it would be in vagina so D
and hormone in 6 i think progesterone ...
Thanks A LOT anyway :D
-
By the way can human excrete carbon dioxide? What else can they excrete then?
YES urea, water, excess salts and ions,Hormone & toxins breakdowns i guess thtss it :)
-
I think so but one i thoiught it would be in vagina so D
and hormone in 6 i think progesterone ...
Thanks A LOT anyway :D
I'm quite sure about 1.
6 or 9? I'll conform it somehow..
EDIT:: Yes, its progesterone. Thanks
-
Please can someone answer my doubts.
-
1.C
2.A
3.A
4.B
5.D
6.D
7.D
8.B
9.B (not sure-sh*t i forgot)
10.B
11.A
12.B
^^someone pls. crosscheck..
for 1, im quite sure that IUCD is used at the uterus. and for 9, it is progesterone.
to 8T,sorry i only answered half of it.did not realize that there was another half to it! ;D
-
UR BRILLIANT :D
+Rep 4 u now :)
haha....thanks! ;D
-
Same here but i have to so imana go .
Sleep well u will need it :)
Byee !
haha..thanks and gud nite!
gudluck for 2morrow!+ cant wait to discuss it! ;D
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Please can someone answer my doubts.
First is A, second is B and third is A in my view. Please correct me if I'm wrong....
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First is A, second is B and third is A in my view. Please correct me if I'm wrong....
Yep A is right for the first one, but why isn't it carbon dioxide, I'm sure CO2 is produced in respiration and CO2 isn't produced in urine?
Dunno about the second one, can someone help please?
And for last one, yes A, but what's the development shown?
-
http://www.freeexampapers.us/IGCSE/Biology/CIE/2009%20Jun/0610_s09_qp_1.pdf
y is no. 22 C ?...can someone plz xplain
-
2. is B. ( it cant be A as if carry two recessive allele, the grandparents will be black in colour.cant be c and d either bcoz if only one is heterozygous that means the other is homozygous - (either both recessive or dominant allele) if both allele are dominant,then all the offsprings will be fine. if both allele are recessive, colour will be black. (its kinda of confusing. hope u understand)
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http://www.freeexampapers.us/IGCSE/Biology/CIE/2009%20Jun/0610_s09_qp_1.pdf
y is no. 22 C ?...can someone plz xplain
Renal artery obviously transports glucose. When filtered, it is reabsorbed back into the renal vein, so there is no presence of glucose in the ureter.
-
Renal artery obviously transports glucose. When filtered, it is reabsorbed back into the renal vein, so there is no presence of glucose in the ureter.
aha ::) thx mate :D
-
Thank god i dont take bio :D , i can see how your suffering.. but i regret it also.. chem today was .. BIO MUCH FIRST 2 PAGES =_="
-
Yep A is right for the first one, but why isn't it carbon dioxide, I'm sure CO2 is produced in respiration and CO2 isn't produced in urine?
Dunno about the second one, can someone help please?
And for last one, yes A, but what's the development shown?
Ivo only urine isn't excretion ;D. Excretion includes removal of waste products of metabolism and Carbon Dioxide is a waste material. Development is increase in complexity by cell enlargement, cell division and morph genesis. I think it's development cause you've got new leaves in it which must have developed from the shoot. Anyway, VIN please (oh wait you're intoxication now ;D) please help. I ain't too confident of that....
-
Thank god i dont take bio :D , i can see how your suffering.. but i regret it also.. chem today was .. BIO MUCH FIRST 2 PAGES =_="
ur actin like my calssmates , they were like *umm so where r we goin out today , to the cinema , ohh no i'll sleep for today * ..that's what they said today and i got soo mad at them ...lol ...(jealous :P :P )
lol...then go to sleep or do smthn fun!! :D :D
-
ur actin like my calssmates , they were like *umm so where r we goin out today , to the cinema , ohh no i'll sleep for today * ..that's what they said today and i got soo mad at them ...lol ...(jealous :P :P )
lol...then go to sleep or do smthn fun!! :D :D
I still have my C2 AS math after 2morow :P , but math is really easy i didnt even start solving pp , just guna do like 1 or 2 :D
-
2. is B. ( it cant be A as if carry two recessive allele, the grandparents will be black in colour.cant be c and d either bcoz if only one is heterozygous that means the other is homozygous - (either both recessive or dominant allele) if both allele are dominant,then all the offsprings will be fine. if both allele are recessive, colour will be black. (its kinda of confusing. hope u understand)
I'm kinda confused. But surely if it was B (it is), then the grandparents will have genotype of Nn. If you cross them, it will be Nn * Nn, which will give offspring: NN, Nn, Nn, nn. But that's 3:1, but it shows 1:1 in the diagram.
Majorly confused.
-
ur actin like my calssmates , they were like *umm so where r we goin out today , to the cinema , ohh no i'll sleep for today * ..that's what they said today and i got soo mad at them ...lol ...(jealous :P :P )
lol...then go to sleep or do smthn fun!! :D :D
hahahaah we did the same thing when our classmates were having their ICT exams. Now, they did with us today :(. Seriously, I'm suing CIE!!! I've lost 5 kgs during the exams, I couldn't watch the champions' league final cause of them exams, i missed england vs japan and i also missed england's friendly today!!! All cause of CIE :D :D...
-
hahahaah we did the same thing when our classmates were having their ICT exams. Now, they did with us today :(. Seriously, I'm suing CIE!!! I've lost 5 kgs during the exams, I couldn't watch the champions' league final cause of them exams, i missed england vs japan and i also missed england's friendly today!!! All cause of CIE :D :D...
u kno we can make a team so that we take our revenge without troublin anyone u kno
i've already teamed up with some
*shhh don't tell the CIE * :P .lol ::)
-
I still have my C2 AS math after 2morow :P , but math is really easy i didnt even start solving pp , just guna do like 1 or 2 :D
well then go study ,what r u doin here :P :P :P
-
well then go study ,what r u doin here :P :P :P
I dunno , i started my holiday already.. and i never have any problems with math.. just find it REALLY easy >_< .. just gunna do one past paper tomorrow then im done :P wohoo
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u kno we can make a team so that we take our revenge without troublin anyone u kno
i've already teamed up with some
*shhh don't tell the CIE * :P .lol ::)
hahaha it's just a joke. LOL. Not that I'm ever going to sue anyone. Surely not CIE. If they give me 5A*s, then God Save the Queen!!!!
-
I'm kinda confused. But surely if it was B (it is), then the grandparents will have genotype of Nn. If you cross them, it will be Nn * Nn, which will give offspring: NN, Nn, Nn, nn. But that's 3:1, but it shows 1:1 in the diagram.
Majorly confused.
yea...i got confused too and honestly, i do not know how to explain it!i just crossed out all the answers that i was sure it was impossible and it left me with B..somebody help us!
-
I dunno , i started my holiday already.. and i never have any problems with math.. just find it REALLY easy >_< .. just gunna do one past paper tomorrow then im done :P wohoo
me too lol
grim , iwas kiddin loooooooooooooool
-
I'm kinda confused. But surely if it was B (it is), then the grandparents will have genotype of Nn. If you cross them, it will be Nn * Nn, which will give offspring: NN, Nn, Nn, nn. But that's 3:1, but it shows 1:1 in the diagram.
Majorly confused.
Listen, listen Ivo you are majorly confused. Yes. See the ratios of male:female is always 1:1 but here you don't have it!!! It's different. It's just a matter of eliminating the wrong ones here. See C and D are definitely not correct. A can't be too either cause you won't have dominant individuals in that situation. So only B is left ;D. Just relax. Listen to Eminem lol and then start again :D :D :D....
-
I'm kinda confused. But surely if it was B (it is), then the grandparents will have genotype of Nn. If you cross them, it will be Nn * Nn, which will give offspring: NN, Nn, Nn, nn. But that's 3:1, but it shows 1:1 in the diagram.
Majorly confused.
By the way, why is the first doubt the answer excretion?
doesnt respiration remove co2 also?
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By the way, why is the first doubt the answer excretion?
doesnt respiration remove co2 also?
Lady where are you!!!! Respiration PRODUCES IT!!! It doesn't remove it. You really need to listen to Eminem lol :D :D :D :D.....
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Lady where are you!!!! Respiration PRODUCES IT!!! It doesn't remove it. You really need to listen to Eminem lol :D :D :D :D.....
haha..thanks!
its almost 2am here.
im too scared to listen to eminem or any other music at this hour! :P
no...seriously, im afraid =,=
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What is the answer? Is it D?
can u plz post question ppr it appear 2 damge in freexam :) :)
-
haha..thanks!
its almost 2am here.
im too scared to listen to eminem or any other music at this hour! :P
no...seriously, im afraid =,=
Don't worry. I'll listen to your share of music :D :D.....
-
Hard doubt, please
-
The answer is Mineral Salts for sure
Hard doubt, please
-
Hey guys plzzzzzz can someone plzz tell me all the answers for the MAY/JUNE 2004 Ppr 1. I looked up the answer in the markscheme on freeexam and on extreme papers but all the answers r wrong even the ones that im 100% sure are right. The MS is giving the wrong answers!! Can someone put it up hurry exam start in like 6 hrs :-[ :'(
-
The answer is Mineral Salts for sure
isnt it nitrogen? from the nitrogenous wastes?
-
The answer is Mineral Salts for sure
Yep I'm with you on this one. See Ivo decaying doesn't produce proteins lol. It doesn't make nitrogen or oxygen. It makes ammonium which is converted to nitrate (in other words the final product is nitrates). And nitrates are mineral salts :D..
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Yep I'm with you on this one. See Ivo decaying doesn't produce proteins lol. It doesn't make nitrogen or oxygen. It makes ammonium which is converted to nitrate (in other words the final product is nitrates). And nitrates are mineral salts :D..
Hey could u pls post the answers for may june 2004 ppr 1 the answers in the MS are all wrong
-
Are you sure??? Give me a minute...
-
Are you sure??? Give me a minute...
Yeah checked the MS on freeexampapers as well as on xtremepapers.com all the answers are coming wrong even the ones that im definitely sure about!!!
Pls hurry vey little time left
-
Hey guys plzzzzzz can someone plzz tell me all the answers for the MAY/JUNE 2004 Ppr 1. I looked up the answer in the markscheme on freeexam and on extreme papers but all the answers r wrong even the ones that im 100% sure are right. The MS is giving the wrong answers!! Can someone put it up hurry exam start in like 6 hrs :-[ :'(
1.D 2.C 3.C 4.B 5.D
6.B 7.B 8.B 9.B 10.D
11.A 12.D 13.C 14.B 15.D 16.D 17.D 18.C 19.A 20.B
21.D 22.C 23.C 24.C 25.B 26.D 27.A 28.A 29.C 30.C
31.B 32.B 33.C 34.A 35.D 36.D 37.D 38.C 39.A 40.A
if ur not sure bout a ques,pliss ask.i may have put in the wrong answer. ^^
-
Don't worry. I'll listen to your share of music :D :D.....
well then, hope you have fun wif that.. :D
-
Yeah checked the MS on freeexampapers as well as on xtremepapers.com all the answers are coming wrong even the ones that im definitely sure about!!!
Pls hurry vey little time left
Which one from the s04 are you having doubts about?
-
1.D 2.C 3.C 4.B 5.D
6.B 7.B 8.B 9.B 10.D
11.A 12.D 13.C 14.B 15.D 16.D 17.D 18.C 19.A 20.B
21.D 22.C 23.C 24.C 25.B 26.D 27.A 28.A 29.C 30.C
31.B 32.B 33.C 34.A 35.D 36.D 37.D 38.C 39.A 40.A
if ur not sure bout a ques,pliss ask.i may have put in the wrong answer. ^^
THanks a lot!!!!!!!!!!!! yupp they r all right. i got sh*t scared cause my exam starts in a few hours and i was like getting all d answers wrong. :)
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Which one from the s04 are you having doubts about?
IN may/ june d answers r all wrong in the MS so dont refer to it k but thanks anyways sumone just posted the answers!!! :)
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IN may/ june d answers r all wrong in the MS so dont refer to it k but thanks anyways sumone just posted the answers!!! :)
[/quote
Dizzy are you sure???? Cause I just did MJ 2004. I only got 2 wrong (which mine were wrong). Are you opening the right document?????
-
This is a strange one. Wording of question is slightly weird.
-
THanks a lot!!!!!!!!!!!! yupp they r all right. i got sh*t scared cause my exam starts in a few hours and i was like getting all d answers wrong. :)
haha...don't worry too much!
if all your answers are wrong, surely theres sumthing wrong with the answers!!
yup mine too!mine starts in another 5 hours and 45 mins more!/color]
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THanks a lot!!!!!!!!!!!! yupp they r all right. i got sh*t scared cause my exam starts in a few hours and i was like getting all d answers wrong. :)
By the way, all of the answers are correct. Just checked with the mark scheme.... I mean SNA's answers...
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This is a strange one. Wording of question is slightly weird.
Regardless of where you look, the image will always be focused on the retina...
-
This is a strange one. Wording of question is slightly weird.
its the retina right?
-
haha...don't worry too much!
if all your answers are wrong, surely theres sumthing wrong with the answers!!
yup mine too!mine starts in another 5 hours and 45 mins more!/color]
By the way, am I the lucky one here?? Cause there are more than 13 hours till my exam :D :D :D...
-
Regardless of where you look, the image will always be focused on the retina...
thanks!
-
By the way, am I the lucky one here?? Cause there are more than 13 hours till my exam :D :D :D...
BUT.... i get freedom first!!!:P haha...bio p1 is my last :P
-
BUT.... i get freedom first!!!:P haha...bio p1 is my last :P
Me too!! But then you get more time to prepare :D :D...
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Me too!! But then you get more time to prepare :D :D...
yea you do...but ive been stuck with this exam for almost a month now! :o
goodbye preparation ( though im not convinced to 100% right) and hallooooo freedom + summers!haha...
all the excitement is keeping me awake. i cant sleep cuz im too fired up!haha...
-
I'm so jealous of you guys. I've still got 8 more to go after Bio P1, before I have freedom at long last!
-
yea you do...but ive been stuck with this exam for almost a month now! :o
goodbye preparation ( though im not convinced to 100% right) and hallooooo freedom + summers!haha...
all the excitement is keeping me awake. i cant sleep cuz im too fired up!haha...
Preparation??? One way or the other I get 38-40 but when I revise stuff, I don't know a thing. Don't get too fired up and sleep. I didn't in Chemistry and lost four marks :(. It was so easy!!! I could've scored 80-79!!!!
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I'm so jealous of you guys. I've still got 8 more to go after Bio P1, before I have freedom at long last!
8 more??? Bloody hell! LOL how many subjects did you opt for???? Well the best thing is that it's over before the world cup! I'm mad after football and hopefully, I'm not going to miss a single match now!!!! :D :D :D...
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I'm so jealous of you guys. I've still got 8 more to go after Bio P1, before I have freedom at long last!
woa!!!thats a lot!!!wat are you taking!why are they torturing you!tats weird..my skul's last igcse is on the 11th of June.is it the same there?
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8 more??? Bloody hell! LOL how many subjects did you opt for???? Well the best thing is that it's over before the world cup! I'm mad after football and hopefully, I'm not going to miss a single match now!!!! :D :D :D...
I'm mad about football as well (not mad, but very interested). Unfortunately, I'm gonna have to miss 1 England game, but that's it. The rest, I'll be there for!!!
Which team do you support By the way? And I have exams for 9 subjects this year.
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Preparation??? One way or the other I get 38-40 but when I revise stuff, I don't know a thing. Don't get too fired up and sleep. I didn't in Chemistry and lost four marks :(. It was so easy!!! I could've scored 80-79!!!!
i didnt sleep for chem either! but not bcoz i was soo fired up, but i was soo nervous.
nah...don't worry bout me.. i had plenty of sleep this evening!you must be gud in chem!!!
im really bad at chem!!!and yes...it was hard for me!!!haha...:D
cant wait to dicuss it tomorrow!
-
So, what do you think about this guys?
-
I'm mad about football as well (not mad, but very interested). Unfortunately, I'm gonna have to miss 1 England game, but that's it. The rest, I'll be there for!!!
Which team do you support By the way? And I have exams for 9 subjects this year.
9 together??? LOL I did 3 in nov 09 and 5 now.
Team? Well my native Pakistan is never going to make it to the world cup and KSA (the place where I live) got knocked out by them North Koreans >:( >:(!! So I'm with England and Netherlands now! Anyone should won it except Brazil!! They've already won it 5 times! Someone else deserves a chance :D. Plus Spain may be favourites but favourites never win do they?? :P :P....
-
So, what do you think about this guys?
D. Just follow the key :D...
-
So, what do you think about this guys?
Horrible picture, a little scary, and a bit fat and belongs to D ;)
-
9 together??? LOL I did 3 in nov 09 and 5 now.
Team? Well my native Pakistan is never going to make it to the world cup and KSA (the place where I live) got knocked out by them North Koreans >:( >:(!! So I'm with England and Netherlands now! Anyone should won it except Brazil!! They've already won it 5 times! Someone else deserves a chance :D. Plus Spain may be favourites but favourites never win do they?? :P :P....
I think it's Spain's lucky year now. And also, are scaly skin and scales the same thing? About the reptile question.
-
So, what do you think about this guys?
i think its class D ^^
-
I think it's Spain's lucky year now. And also, are scaly skin and scales the same thing? About the reptile question.
yup!
-
Please can someone answer my doubts.
I know it's B, but can anyone explain why? Apart from process of elimination.
-
yup!
Purple you fav. colour?
-
Horrible picture, a little scary, and a bit fat and belongs to D ;)
hahahahah very accurate!!! :D....
-
Also, why do epidermal cells contain no chloroplasts?
And so it looks like (from past papers) that artery is an organ then. How odd! I thought it was a tissue.
Xylem tubes have no end walls? What are end walls?
-
Also, why do epidermal cells contain no chloroplasts?
And so it looks like (from past papers) that artery is an organ then. How odd! I thought it was a tissue.
Xylem tubes have no end walls? What are end walls?
end walls is like a barrier that stops smthn from passin ..and in xylem there is no in order to transport water and salts up to the leaves .
nah it is an organ ...but if they point at a part of it then it's a tissue ;)
in order for the palisade cells to receive max light intesity to photosynthesize then the epidermis is transparent hence no chloropasts ;)
got it ?
-
Purple you fav. colour?
yup! again! ;D
haha..its actually pink and purple,but the pink colour is too light!hard for people to c! :)
hm..let me guess your..maybe black or dark blue i suppose?haha..or orange!!!wait...maybe white!
did i get any correct? ??? haha..
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yup! again! ;D
haha..its actually pink and purple,but the pink colour is too light!hard for people to c! :)
hm..let me guess your..maybe black or dark blue i suppose?haha..or orange!!!wait...maybe white!
did i get any correct? ??? haha..
yea pink is too light..
Black and orange! :D nice guess!.. :)
-
Black, black and nothing but black!!!!!!!!!!!!!!!!! The colour of elegance!!!
-
Black, black and nothing but black!!!!!!!!!!!!!!!!! The colour of elegance!!!
lol me too ::)
-
How about this question. The answer in the mark scheme from this paper and the same from s03, have completely different answers. I'm clueless.
-
How about this question. The answer in the mark scheme from this paper and the same from s03, have completely different answers. I'm clueless.
can u gimme the link ...............and y r u clueless ?! :-\ i just xplained it to u :-X
-
How about this question. The answer in the mark scheme from this paper and the same from s03, have completely different answers. I'm clueless.
C.
-
How about this question. The answer in the mark scheme from this paper and the same from s03, have completely different answers. I'm clueless.
C C C and only C!!! Just consider the mark scheme for S03. Those are the OFFICIAL ones...
-
guys it nice was talkin/watchin ya talk :P ...lol... anyways i really MUST go to bed or my head will explode ..
nighty nighty :-* lol :P :P :P
-
C.
Is the reason it's C and not D, becuase it rotating so no change in geotropism?
Also, for this question, why chromosome and not allele?
-
Is the reason it's C and not D, becuase it rotating so no change in geotropism?
Also, for this question, why chromosome and not allele?
Listen alleles are for genes and genes are on chromosomes! You have sex chromosomes not sex alleles....
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Is the reason it's C and not D, becuase it rotating so no change in geotropism?
Also, for this question, why chromosome and not allele?
cuz u as a male have chomosomes in ur nuclues and this is a Y gene
FYI what defines whether u r a female or male is ur CHROMOSOMES hence whether it's Y or X ..and as a guy u have a Y CHROMOSOME
got it ?
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Black, black and nothing but black!!!!!!!!!!!!!!!!! The colour of elegance!!!
yes yes ... i do agree..black is like the classic colour and its simple.
on top of that, all colours go with it!but i still like purple and pink simply because its sweet and soft
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guys it nice was talkin/watchin ya talk :P ...lol... anyways i really MUST go to bed or my head will explode ..
nighty nighty :-* lol :P :P :P
gud nite and gudluck for tomorrow!!!
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cuz u as a male have chomosomes in ur nuclues and this is a Y gene
FYI what defines whether u r a female or male is ur CHROMOSOMES hence whether it's Y or X ..and as a guy u have a Y CHROMOSOME
got it ?
hahah was that for me or Ivo??? Cause Ivo doesn't really look like a boy :P :P....
-
gud nite and gudluck for tomorrow!!!
u too ;)
nah it was for Ivo , no he is a boy!!
-
By the way, how many papers have you been doing? And do you think I should read the textbook or do more papers?
-
u too ;)
nah it was for Ivo , no he is a boy!!
Or am I, nah... only jokin I'm a dude!
-
By the way, how many papers have you been doing? And do you think I should read the textbook or do more papers?
for ur case i believe that u have either forgotten or not really understood some concepts hence i suggest u read ur textbook if u have time and then do more past papers ;)
Ivo : i kno that already loool
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u too ;)
nah it was for Ivo , no he is a boy!!
:O :O :O! Don't mind it Ivo but that's an odd picture for a boy. Anyway, your world your choice! Scarface: The world is yours!!! :D :D...
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:O :O :O! Don't mind it Ivo but that's an odd picture for a boy. Anyway, your world your choice! Scarface: The world is yours!!! :D :D...
WTH , let him choose the pic he wants to put up ..lol....
cuz for me if i wish to put a pic of a boysish kind , u ain't stopin me from doin so neither will anyone else ;)
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yo i really MUST go ..............chaw 8)
* snores *
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Yeah, I need to go as well. I've got an English exam in the morning and Bio P1 as well :(
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WTH , let him choose the pic he wants to put up ..lol....
cuz for me if i wish to put a pic of a boysish kind , u ain't stopin me from doin so neither will anyone else ;)
LOL that's what I said ;D.. Anyway, good luck people. Hope it goes well for everyone. AND I'LL BE FREE TOMORROW!!! HURRAY!!!!!!
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Hey people Best of Luck! Do well! (golden girl, y didn't you say "Kill the paper"? :P)
Anyway good night! 5 am here, still not slept, hungry and exam is in 3 1/2 hrs! :@ ! :o
What do you guys say? Should I sleep or not? :P
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Hey people Best of Luck! Do well! (golden girl, y didn't you say "Kill the paper"? :P)
Anyway good night! 5 am here, still not slept, hungry and exam is in 3 1/2 hrs! :@ ! :o
What do you guys say? Should I sleep or not? :P
3.5 hours???? Man take a bath for one hour with warm water and then watch a good movie :D. Don't sleep :D.....
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WAIT PEOPLE!!!don't GO ANYWHERE!!I HAVE SUMTHING TO SHOW YOU GUYS!!AND ITS COOL!
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WAIT PEOPLE!!!don't GO ANYWHERE!!I HAVE SUMTHING TO SHOW YOU GUYS!!AND ITS COOL!
?????????????
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as promised,here it is!
(http://sphotos.ak.fbcdn.net/hphotos-ak-ash1/hs503.ash1/29784_116094388432005_100000943347947_85318_5866711_n.jpg)
GOOD LUCK TO ALL!!!!
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Nice on SNA! That'll surely give my maths teacher a real headache :D....
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Nice on SNA! That'll surely give my maths teacher a real headache :D....
this is how we teenagers use our maths skills!!haha.... ;D
i might say that we are smarter!i bet our maths teacher never thought of that!
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1.C
2.A
3.A
4.B
5.D
6.D
7.D
8.B
9.B (not sure-sh*t i forgot)
10.B
11.A
12.B
^^someone pls. crosscheck..
the 9 (C) progestrone
ogestrone is responsible female secondary charcacteristic
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the 9 (C) progestrone
ogestrone is responsible female secondary charcacteristic
thanks!
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Hey people Best of Luck! Do well! (golden girl, y didn't you say "Kill the paper"? :P)
Anyway good night! 5 am here, still not slept, hungry and exam is in 3 1/2 hrs! :@ ! :o
What do you guys say? Should I sleep or not? :P
well then ......KILL the paper amigos :D :D :D ..lol ::)
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wen du u guyz hv bio?
n im sure u all ll ;D
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wen du u guyz hv bio?
n im sure u all ll ;D
both me an intoxicated/Vin did it :D ..
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Hey people Best of Luck! Do well! (golden girl, y didn't you say "Kill the paper"? :P)
Anyway good night! 5 am here, still not slept, hungry and exam is in 3 1/2 hrs! :@ ! :o
What do you guys say? Should I sleep or not? :P
dude....have u been drinking all day??
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hahaha why do you ask? cuz his name's intoxication and he coincidentally stayed up all night? lol
yeah...i think he's been celebrating b4 the exam....
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Oye Intoxiation, tu sharabi tau nahin hai na. :P
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Oye Intoxiation, tu sharabi tau nahin hai na. :P
wth is that? 8)
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lol...it jst means "ur not a drunkard rite?"
its in urdu :D
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lol...it jst means "ur not a drunkard rite?"
its in urdu :D
HINDI !!!!!
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hindi!
isnt it the same??
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HINDI !!!!!
Urdu!!! Cause neither him nor me know hindi :D..
Basically the same. Difference in writing and some words. You know like terrorists are atangwadi in hindi, dashatgard in urdu lol :D :D....
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you guys how come animals and decomposers depend on light for their energy? :S isn't that just plants?
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nope indirectly all organisms depend on light for energy, because we eat plants, or animals that have eaten plants. and all plants require energy (from sunlight) to photosynthesize and produce food
think about it, if there were no plants, primary consumers would die out, then secondary would, then tertiary would, then we would!
get it?
yeaa i was thinking abt it that way too :) guess i was sleepy last night :P thanks!
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http://www.freeexampapers.us/IGCSE/Biology/CIE/2008%20Jun/0610_s08_qp_1.pdf
can someone please explain why in number 5 the cell is in the palisade mesphyll and not the leaf epidermis?? leaf structures are so confusing can someone please give me a concise but informative overview?
oh and why on earth is number 18 D?????
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http://www.freeexampapers.us/IGCSE/Biology/CIE/2008%20Jun/0610_s08_qp_1.pdf
can someone please explain why in number 5 the cell is in the palisade mesphyll and not the leaf epidermis?? leaf structures are so confusing can someone please give me a concise but informative overview?
oh and why on earth is number 18 D?????
Q5: There are loads more chloroplasts in the pallisade mesophyll cell than normal, so it must be that.
Q18: Obviously D, lungs, because they oxygenate deoxygenated blood and pass this oxygenated blood to the pulmonary vein and into the left chamber.
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Can someone please explain to me the answer of Biology paper 1 Q2 year 2001?? ??? ??? ???
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Q5: There are loads more chloroplasts in the pallisade mesophyll cell than normal, so it must be that.
Q18: Obviously D, lungs, because they oxygenate deoxygenated blood and pass this oxygenated blood to the pulmonary vein and into the left chamber.
but dont the the cells in the epidermis also have loads of chloroplasts??
and the diagram in 18 doesn't show that :S it shows X receiving oxygenated blood and passing on deoxygenated blood!!
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Can someone please explain to me the answer of Biology paper 1 Q2 year 2001?? ??? ??? ???
well if you're talking abt may/june then the explanation is simple; P can't be genus or species cuz "feathers and wings" aren't part of the name. The genus is the first part of an organism's name and the first letter is uppercase (caps) and the second part of the name is the speicies and its in lowercase. so P is class. Q is the full name of the organism so it's species.
i dont have the question paper for november sorry
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3.5 hours???? Man take a bath for one hour with warm water and then watch a good movie :D. Don't sleep :D.....
Oh man! This was a really good idea! (I'd have slept in the bath for sure!). Good movie? I feel Eminem songs are better :P Unfortunately I slept :-\ :P
well then ......KILL the paper amigos :D :D :D ..lol ::)
^^Your trademark ;) :D Hope you did the paper well..
i like your new name lol
did you sleep???? i know this is late, but i think you should have! lol i went to bed at 1.
arghhh how was your paper? have you finished? i have a couple questions to ask :-\ >:(
Thank you! Yup I slept for 3hrs. Almost reached in time for the exam.. :) 1am.. I see. I cannot sleep before that! ;D
Sure I'm online
dude....have u been drinking all day??
hahaha why do you ask? cuz his name's intoxication and he coincidentally stayed up all night? lol
How did you guess? ::) :P :P joke! :D
That was the idea..
Oye Intoxiation, tu sharabi tau nahin hai na. :P
Bilkul nahi!
Hope you guys did the paper well! :D
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Vin ?? LOL !! You changed your name to intoxication ? :D :D :D
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Vin ?? LOL !! You changed your name to intoxication ? :D :D :D
Yea dude, that's me. ;) :D
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Oh man! This was a really good idea! (I'd have slept in the bath for sure!). Good movie? I feel Eminem songs are better :P Unfortunately I slept :-\ :P
^^Your trademark ;) :D Hope you did the paper well..
Thank you! Yup I slept for 3hrs. Almost reached in time for the exam.. :) 1am.. I see. I cannot sleep before that! ;D
Sure I'm online
How did you guess? ::) :P :P joke! :D
That was the idea..
Bilkul nahi!
Hope you guys did the paper well! :D
NOT AFRAID !! NO FEAR IGCSE !! ;D
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People how did your exam go??? Thank God mine was great! If I could moonwalk like Michael Jackson, I would've done it!!! :D :D....
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People how did your exam go??? Thank God mine was great! If I could moonwalk like Michael Jackson, I would've done it!!! :D :D....
Mine was good too! :D ha ha I can do a moonwalk. :P
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Mine was good too! :D ha ha I can do a moonwalk. :P
Hahha you're lucky lad....
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YESS! DONE WITH IGs!!!
FINALLY SUMMMMMER!
Oh and the paper was good ;D
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YESS! DONE WITH IGs!!!
FINALLY SUMMMMMER!
Oh and the paper was good ;D
Yes! And done solving doubts. :P
Its already monsoon here.
Glad it was good. :)
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NO MORE CHEM YAY
NO MORE BIO FOR A SUMMER LOL XD glad its over man load on the chest
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General question: what happens if humans breathe in insecticides, e.g. what you'd use to kill cockroaches?
I dont do bio but I'd say that the level of toxins in your body would increase, but if you dont breathe it in for too long you should be fine.
However, those really strong ones can kill you in even small quantities; they're the ones used by those pest control guys.
Why ?
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hey guys how water vapour moves???
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from the leaves think transpiration..
but it moves with diffusion cause water vapour, if water osmosis
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guys can u send me all ur bio and chem resources that u depended on at odelavego@yahoo.com
help a brother so that god will help u
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guys can u send me all ur bio and chem resources that u depended on at odelavego@yahoo.com
help a brother so that god will help u
http://www.biology-questions-and-answers.com/index.html <------------ Good site for Bio.
http://www.docbrown.info <-------------- The God of Chem :P
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HI.
Im writing my Igcse paper in 2012 and I was wondering if you have any tips in getting an A* in Biology and Chemistry? My biology has been going pretty well but my chemistry. well thats a totally different story.
Do you know any websites one could practice Stochiometry and the mole concept?
Thanks.
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The best way I can help is if you give me a question; then I'll solve it for you step by step.
Chem is easy (I got an A* in it), you just have to work your butt off :P
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HI.
Im writing my Igcse paper in 2012 and I was wondering if you have any tips in getting an A* in Biology and Chemistry? My biology has been going pretty well but my chemistry. well thats a totally different story.
Do you know any websites one could practice Stochiometry and the mole concept?
Thanks.
Heyy :) welcome to SF (: I have attached a file which was a great help to me :) Hope u find it helpful :)
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Oh my god.
Thank you so much :)
I am so scared for my Igce's.
any tips for preparing?
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Oh my god.
Thank you so much :)
I am so scared for my Igce's.
any tips for preparing?
Theres nothing to worry abt :) learn the concepts and do LOTS of past papers :) if in doubt just post the doubt here and we will solve it for u :)
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Oh okay thank you so much once again :)
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Oh okay thank you so much once again :)
Post any doubts here - we'll answer them.
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Oh my god.
Thank you so much :)
I am so scared for my Igce's.
any tips for preparing?
Past papers, past papers....& past papers ::)
Read your content well. if you have problem understanding anything, post here, one of us will answer :)
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If you want to succeed in Chemistry say these 3 magic words :
I LOVE CHEM !!!!
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Lmao Ari...
Just do lots of past year papers and listen well in class. I didn't expect to get an A star, but I did and all I did was doing what I just said. I didn't even revise much. XD