Post by: Saladin on April 04, 2010, 04:28:00 pm
Just trying out the tex editor.
Post by: Sue T on April 06, 2010, 04:55:15 pm
past paper says:
The equilibrium constant, Kc, for the reaction to form ethyl ethanoate from ethanol and ethanoic
acid, C2H5OH + CH3CO2H CH3CO2C2H5 + H2O, at 60(degree)C is 4.00.
When 1.00 mol each of ethanol and ethanoic acid are allowed to reach equilibrium at 60(degree)C, what
is the number of moles of ethyl ethanoate formed?
A 1/3
B 2/3
C 1/4
D 3/4
Post by: 3ishakay on April 06, 2010, 05:55:25 pm
i hope chemistry doubts go here as well
past paper says:
The equilibrium constant, Kc, for the reaction to form ethyl ethanoate from ethanol and ethanoic
acid, C2H5OH + CH3CO2H CH3CO2C2H5 + H2O, at 60(degree)C is 4.00.
When 1.00 mol each of ethanol and ethanoic acid are allowed to reach equilibrium at 60(degree)C, what
is the number of moles of ethyl ethanoate formed?
A 1/3
B 2/3
C 1/4
D 3/4
hey ... dyu noe the anser to tht?
wht paper ist frm?
im thinkn the anser is B = 2/3
this is how i did it ..(any1 tell me if i got it wrong .. plz!!)
ethanol + ethanoic acid -----> ethylethanoate + water
C2H5OH + CH3CO2H -------> CH3CO2C2H5 + H2O
b4 eq. 1 1 0 0
aftr eq. 1-x 1-x x x
thn Kc= [ethylethanoate][water]
-----------------------
[ethanol][ethanoic acid]
so its like
[ x]^2 = 4
--------
[1-x]^2
thn u ju solv it like in maths ..
and thn u get 2/3 =D
rechek the smae crap..
go
( 2/3)^2 = 4!! TADA!!! :D:D:D
----------
(1/3)^2
Post by: nid404 on April 06, 2010, 06:05:15 pm
Post by: 3ishakay on April 06, 2010, 06:10:19 pm
hey Thanks :)
not a prbm 8) ;)
Post by: ruby92 on April 06, 2010, 06:11:54 pm
Post by: nid404 on April 06, 2010, 06:12:49 pm
the answer is b??? ???
U have doubts??
Wait, I'll check her post agn
Post by: ruby92 on April 06, 2010, 06:17:10 pm
Post by: 3ishakay on April 06, 2010, 06:19:30 pm
lool no...i get it..i was checking i didnt read 3ishakay post :P
lol cool ..
By the way im not sure abt my post .
i always use the revers method cus its fastr.
im not evn sure if the math bit turns out ryt .. :P
Post by: nid404 on April 06, 2010, 06:19:41 pm
Post by: halosh92 on April 06, 2010, 07:15:39 pm
could u just explain how to solve this question step by step please?
Jill is swimming across a river which has constant current of "k m/s". if jill heads directly across the river with speed "v m/s"
find her resultant speed and the angle her path makes with a line directly across the river when
k= 2
v=1
thx alot ;D
Post by: Saladin on April 06, 2010, 07:18:03 pm
Post by: Saladin on April 06, 2010, 07:23:09 pm
PHYSICS AS
could u just explain how to solve this question step by step please?
Jill is swimming across a river which has constant current of "k m/s". if jill heads directly across the river with speed "v m/s"
find her resultant speed and the angle her path makes with a line directly across the river when
k= 2
v=1
thx alot ;D
this is a simple trigonometric question.
electricity going again
srry cud not reply
cant scan the thing
will wen i can
thanks
hope u guys dnt mind.
Post by: Sue T on April 07, 2010, 09:04:59 am
thanx!
Post by: nid404 on April 07, 2010, 09:51:32 am
PHYSICS AS
could u just explain how to solve this question step by step please?
Jill is swimming across a river which has constant current of "k m/s". if jill heads directly across the river with speed "v m/s"
find her resultant speed and the angle her path makes with a line directly across the river when
k= 2
v=1
thx alot ;D
R= root of k2 + v2
= root of 5
tan theta= k/v=2
theta= 63.43o clockwise down the stream
Post by: sweetie on April 07, 2010, 07:11:32 pm
cud u plz help me in Q.30> the ms says 'A' but why is it not ethanol?
Q.20> ms says "c"
Q.2> ms says ' B'
ruby, is it chemistry?
Post by: nid404 on April 07, 2010, 07:18:52 pm
Thanks
Post by: ruby92 on April 07, 2010, 07:27:16 pm
more chemistry doubts..ohh sorryy yeh
cud u plz help me in Q.30> the ms says 'A' but why is it not ethanol?
Q.20> ms says "c"
Q.2> ms says ' B'
ruby, is it chemistry?
Post by: sweetie on April 07, 2010, 07:38:21 pm
so, in 'P' 6*18 = 108g of water r absorbed which = increase in mass at P
at Q 6*44=264g of CO2 r absorbed = increase in mass at Q
so 108/ 264= 0.41 = Mp/ Mq
hope u understud 8)
Post by: ruby92 on April 07, 2010, 07:43:13 pm
paper 2 O/N 2003 Q3...
all the parts with the calculations involved ??? ???
Post by: nid404 on April 07, 2010, 07:51:00 pm
or do u want the whole q to be done?
Post by: ruby92 on April 07, 2010, 08:02:51 pm
cii and d
Post by: nid404 on April 08, 2010, 07:40:35 am
=200x4.2X12.2=10.25KJ
iii) 1g gives out 10.25 KJ
1 mole=??
1 mole of calcium=40.1g
so H released with 40.1g=40.1X10.25=- 411KJ/mol exothermix(heat released)
c)ii) Ca(s) + 2H2O(l) ? Ca(OH)2(aq) + H2(g) ?H = –411
dh of formation of water= -286kJ/mol since 2 moles of water =2X-286= - 572
dh reaction= h of products-h of reactants
-411 = X- (-572)
X= -411-572=-983KJ/mol
d) In b(ii) 1g of Ca ws used...1g of ca= 1/40.1 moles=0.025moles
Ratio of Ca:H2=1:1
therefore 0.025 moles of H2 formed
1 moles occupies 24dm3
0.025mol=0.025X24=0.6dm3/ 600cm3
Post by: sweetie on April 08, 2010, 09:52:57 am
more chemistry doubts..
cud u plz help me in Q.30> the ms says 'A' but why is it not ethanol?
Q.20> ms says "c"
Q.2> ms says ' B'
plzzzzzzzz, sum1 answer my que's >:(
Post by: nid404 on April 08, 2010, 10:08:36 am
We all have to study here....some1 will always answer when free
2) 30% x= 144
x=144X100/30=480g
P2=32X2=64g
% of P2= 64/480 X100
=13.1%
20) U have to try out all the possible outcomes with 4 carbons
You get 5 possibilities....try it
30) Ethanol will not react with NaOH at all....
Ethanol will only react with metals, not metal compounds..keep that in mind
Post by: sweetie on April 08, 2010, 12:12:19 pm
for Q20. i got da 3 structural isomers( primary, secondary & tertiary)
one cis and trans.
1 optical isomers and its reflection
and this adds up to 7 ???
OR do we consider both the cis and trans as 1 isomer?
Post by: ruby92 on April 08, 2010, 12:27:28 pm
stereo isomerism is only possible for compounds with a double bond
they can have 5 structural only, ie primary alcohol and secondary alcohol and tertiary alcohol, two of the methyl groups can also be shifted.
ans is therefore C) 5
Post by: sweetie on April 08, 2010, 12:59:30 pm
but optical isomers dont have
double bonds ,
so ya 3 structural and 2 optical, which adds up to 5..... rite??
Thank You :-*
Post by: ruby92 on April 08, 2010, 01:29:39 pm
i think ur pretty much rite
Post by: sweetie on April 08, 2010, 01:45:02 pm
Q.19. i never get such que's rite, any hint...
Q20. i found 6 but the ms says 8.. how???
Q28. isnt it dat 1molecule of 2,4 DNPH is needed for each ketone grp ( By the way what's X )??
thanks 4 any help :-*
Post by: nid404 on April 08, 2010, 05:47:13 pm
I'll circle the carbons which have a chiral center...check the attachment
Post by: sweetie on April 08, 2010, 06:15:39 pm
Post by: nid404 on April 08, 2010, 06:17:43 pm
Post by: sweetie on April 08, 2010, 06:29:25 pm
got it :-*
Post by: nid404 on April 08, 2010, 06:29:51 pm
Post by: nid404 on April 08, 2010, 06:39:04 pm
further if u consider the whole chain, ull find 2 more...
actually it'll take tooooooo much time to draw the whole thing out....but if u really want it, i shall do it tom and scan it
28)2,4 DNP reacts with carbonyl compound with C=O group
1 already present...
2 formed at the other 2 double bonds
Post by: sweetie on April 08, 2010, 07:56:07 pm
thanx so much , i really appreciate ur help :-*
cud u also help me in Q4 , 29 of da same year???
Post by: nid404 on April 09, 2010, 06:02:20 am
Post by: nid404 on April 09, 2010, 06:14:24 am
Q4) D
first thing when u c these graphs..look for the obvious
you know 18 protons/eletcrons....electronic configuration 2.8.8 so 0 unpaired electrons....it will be either B or D
Now look at the other proton numbers....you knw electrons are filled singly until there is no more space to....
So upto proton no 15, it is filled singly, no of unpaired electrons increase. Then, they start pairing up, after proton no 15, reducing the no of unpaired electrons.
eg. take 15 electrons
1s22s22p63s2 3p3
the 3 electrons in the p subshell are in the 3 different orbitals and so 15 has the max no of unpaired electrons...3
Post by: nid404 on April 09, 2010, 06:18:25 am
check where the OH groups r
in A, B n C if dehydration happens, double bonds will form as shown in the compound but in D, one OH group is in the centre, which will not give a double bond like desired in the two ends.
I hope ur getting me :-\
Post by: sweetie on April 09, 2010, 04:09:52 pm
Thank You :-*
Post by: sweetie on April 09, 2010, 05:42:39 pm
A carbon dioxide
B helium
C hydrogen
D nitrogen
da answer for this is helium, but why cant it be hydrogen?
Post by: nid404 on April 09, 2010, 05:44:57 pm
It will have intermolecular force...they exist as diatomic molecules which is not close to being an ideal gas at all
Post by: ruby92 on April 09, 2010, 06:05:02 pm
Q 28
39(why is 2 wrong?)
35(why not 3)
34(why is 3 right, wont half filled orbitals have high IE values?)
33(why not 2 and 3)
m/j 2004 paper 1
28) D agn
monosubstituted alkene, one R group is attached to the carbon-carbon double bond. Not oxidized by mild oxidising agents
i dont understand this
??? ???
Post by: Sue T on April 11, 2010, 11:03:53 am
w 02
3) Use of the Data Booklet is relevant to this question.
In the gas phase, aluminium and a transition element require the same amount of energy to form
one mole of an ion with a 2+ charge.
What is the transition element?
A Co
B Cr
C Cu
D Ni
the other 2 are attached -i couldnt copy paste
mj06
2 A sample of chlorine containing isotopes of mass numbers 35 and 37 was analysed in a
mass-spectrometer.
How many peaks corresponding to Cl2+ were recorded?
A 2
B 3
C 4
D 5
Post by: nid404 on April 11, 2010, 11:07:01 am
Post by: ruby92 on April 11, 2010, 12:46:32 pm
3.(from the data booklet) Al has a 1st I.E. of 577 and a 2nd I.E. of 1820
so the total i.e. when forming an ion with a 2+ charge is 577+1820=2397
(also from data booklet) Co has a 1st I.E. of 757 and 2nd I.E. of 1640
so the total energy to form a 2+ charge is also 2397
therefore the answer is A
w06
i dont get this ??? :(
Post by: Amr Fouad on April 11, 2010, 12:55:19 pm
i have some more chem questions :
w 02
3) Use of the Data Booklet is relevant to this question.
In the gas phase, aluminium and a transition element require the same amount of energy to form
one mole of an ion with a 2+ charge.
What is the transition element?
A Co
B Cr
C Cu
D Ni
the other 2 are attached -i couldnt copy paste
mj06
2 A sample of chlorine containing isotopes of mass numbers 35 and 37 was analysed in a
mass-spectrometer.
How many peaks corresponding to Cl2+ were recorded?
A 2
B 3
C 4
D 5
mj 2006:
answer is B (3)
u have a 3 types of chlorine molecules
(35,35)
(35,37)
(37,37)
i.e one chlorine atom with 35,other with 37, etc..
Post by: ruby92 on April 11, 2010, 12:57:07 pm
mj 2006:
answer is B (3)
u have a 3 types of chlorine molecules
(35,35)
(35,37)
(37,37)
i.e one chlorine atom with 35,other with 37, etc..
could u explain this in more detain please ??? ???
Post by: nid404 on April 13, 2010, 07:12:28 am
w02Yup, that's how it is for the first one...
3.(from the data booklet) Al has a 1st I.E. of 577 and a 2nd I.E. of 1820
so the total i.e. when forming an ion with a 2+ charge is 577+1820=2397
(also from data booklet) Co has a 1st I.E. of 757 and 2nd I.E. of 1640
so the total energy to form a 2+ charge is also 2397
therefore the answer is A
w06
i dont get this ??? :(
nov 06..which q?
Post by: Amr Fouad on April 13, 2010, 07:15:45 am
could u explain this in more detain please ??? ???
alright..here is the deal..chlorine is a diatomic element that consists of 2 atoms paired up, right?
there are 2 isotopes of chlorine, 35 and 37..therefore, it is possible to have only 3 combinations of these 2 isotopes..
1) a diatomic molecule with one 35 Cl atom, and 1 35 Cl atom
2) a diatomic molecule with one 35 Cl atom, and 1 37 Cl atom
3) a diatomic molecule with one 37 Cl atom, and one 37 Cl atom
got that?
Post by: nid404 on April 13, 2010, 07:22:29 am
could u explain this in more detain please ??? ???
Chlorine has two isotopes, 35Cl and 37Cl, in the approximate ratio of 3 atoms of 35Cl to 1 atom of 37Cl. You might suppose that the mass spectrum would look like this:
(http://www.chemguide.co.uk/analysis/masspec/clmasspec.GIF)
The problem is that chlorine consists of molecules, not individual atoms. When chlorine is passed into the ionisation chamber, an electron is knocked off the molecule to give a molecular ion, Cl2+. These ions won't be particularly stable, and some will fall apart to give a chlorine atom and a Cl+ ion. The term for this is fragmentation.
(http://www.chemguide.co.uk/analysis/masspec/cl2eq.GIF)
If the Cl atom formed isn't then ionised in the ionisation chamber, it simply gets lost in the machine - neither accelerated nor deflected.
The Cl+ ions will pass through the machine and will give lines at 35 and 37, depending on the isotope and you would get exactly the pattern in the last diagram. The problem is that you will also record lines for the unfragmented Cl2+ ions.
Think about the possible combinations of chlorine-35 and chlorine-37 atoms in a Cl2+ ion.
Both atoms could be 35Cl, both atoms could be 37Cl, or you could have one of each sort. That would give you total masses of the Cl2+ ion of:
35 + 35 = 70
35 + 37 = 72
37 + 37 = 74
That means that you would get a set of lines in the m/z = 70 region looking like this:
(http://www.chemguide.co.uk/analysis/masspec/cl2masspec.GIF)
The overall mass spectrum looks like this:
(http://www.chemguide.co.uk/analysis/masspec/cl2overallms.gif)
yaa?
Post by: Metallicnak on April 13, 2010, 03:37:49 pm
1) Does a material vibrates at its maximum amplitude when its at its fundamental frequency compared to its other modes of vibration. If so then isnt fundamental frequency of a material the same thing as the materials natural frequency.
2) Can someone tell me the differences between a single slit interference and double slit and if light can produce an interference pattern through a single slit, when one of the double slits are covered sholdnt an interference pattern still be noticed?
3) Explanation of doppler effect when the observer is moving towards the source of sound.
Guys if u could speed up on ur replys i would be grateful hve a mock exam tommorow :-\
Much help appreciated! :)
Post by: Sue T on April 14, 2010, 10:42:22 am
if any1 would kindly check the attached questions (just 2 more of paper 1) - i've been carrying them around 4 more than a month now - no 1 seems 2 no how 2 do em..
Post by: sweetie on April 14, 2010, 06:33:42 pm
Post by: nid404 on April 14, 2010, 07:36:24 pm
Post by: Amr Fouad on April 14, 2010, 07:48:24 pm
Sorry to break up all the Chem discussions guys :P but I need to get some physics doubts straight here.
1) Does a material vibrates at its maximum amplitude when its at its fundamental frequency compared to its other modes of vibration. If so then isnt fundamental frequency of a material the same thing as the materials natural frequency.
2) Can someone tell me the differences between a single slit interference and double slit and if light can produce an interference pattern through a single slit, when one of the double slits are covered sholdnt an interference pattern still be noticed?
3) Explanation of doppler effect when the observer is moving towards the source of sound.
Guys if u could speed up on ur replys i would be grateful hve a mock exam tommorow :-\
Much help appreciated! :)
1) First of all, do not confuse the fundamental frequency with the natural frequency. From your doubts I believe you are doing Edexcel Physics AS.
And the fundamental frequency does not mean vibration at the maximum amplitude, as you have infinite multiples of the fundamental frequency; first harmonic, second harmonic, etc..
2) Interference occurs only when you have to sources of waves. Thats the main difference between single and double slits. In a single slit, diffraction only occurs. But in a double slit, interference occurs due to diffraction of waves.(http://www.phy.ntnu.edu.tw/ntnujava/snapshotejs/20_smf_doubleSlit_20090118003214.gif)
There is NO INTERFERENCE IN SINGLE SLITS.
3) The examiner never gives you the situation where the observer moves towards the source, the opposite happens. Check out this video.. It is really helpful [yt=425,350]http://www.youtube.com/watch?v=-t63xYSgmKE[/yt]
Sorry for the late reply.. I just got your post :-\
Post by: sweetie on April 14, 2010, 09:03:04 pm
Making it alkaline would be adding more hydroxyl anions...when conc of OH- ions increase, equilibrium will shift to the left to resist the change(le chateliers)
isnt precipitating more V3+ ions has the same effect , so why is option B wrong?????
Post by: nid404 on April 15, 2010, 05:15:30 am
So what they mean by precipitating V3+ ions is the already existing V3+ ions are being precipitated, they are dissolved prior to the addition...there's no change in conc/amount of V3+ ions, only the existing ions dissolved would be precipitated, this will not bring about a change in equilibrium
Post by: Metallicnak on April 15, 2010, 05:02:39 pm
Thanks again.
Post by: Amr Fouad on April 15, 2010, 05:07:15 pm
Thanks for the info ~ A.F ~ preety much cleared all the doubts :D, By the way no probs on the delay.
Thanks again.
Any time mate :)
Post by: halosh92 on April 15, 2010, 08:59:21 pm
q9
plzz someone explain in detailed steps how to do it :SS
thxx its URGENT
Post by: Amr Fouad on April 15, 2010, 11:21:47 pm
Post by: Amr Fouad on April 16, 2010, 12:28:19 am
Hope that helped :)
Post by: Sue T on April 16, 2010, 01:42:47 pm
38 Which compounds would be formed in the reaction of ethene with aqueous bromine in the
presence of sodium chloride?
1 CH2ClCH2Cl
2 CH2BrCH2Cl
3 CH2BrCH2Br
the answer is 2&3
but wat if after ethene & bromine formed dibromoethane, the Cl in NaCl replaces one Br n then th next Br is replaces by NaCl as well (since we dont no how many NaCl(s) r present) wodnt we end up w/ CH2ClCH2Cl ?
y is tht rong?
Post by: pjb13 on April 16, 2010, 09:35:42 pm
Loan capital is an important source of finace for many businesses. However unlike share capital, taking on an additional loan capital does not compromise ownership. Highly geared firms, whose share capital is made up mostly of loan capital, can be highly vulnerable to interest rate changes, particularly if they have not borrowed at a fixed rate. A sudden increase in the interest rate will increase their fixed costs, leading to lower profits.
Can anyone explain the exact meaning of share and loan capital? i dont get the sent in bold.
Post by: Saladin on April 17, 2010, 04:13:55 pm
Its abt Business St: If market supply decreases, but market demand does not, competition will increase. I dont get how competition increases ?
Loan capital is an important source of finace for many businesses. However unlike share capital, taking on an additional loan capital does not compromise ownership. Highly geared firms, whose share capital is made up mostly of loan capital, can be highly vulnerable to interest rate changes, particularly if they have not borrowed at a fixed rate. A sudden increase in the interest rate will increase their fixed costs, leading to lower profits.
Can anyone explain the exact meaning of share and loan capital? i dont get the sent in bold.
For the first part:
Well your supply is decreasing, and thus with the same amount of demand, the supply is lower then it was previously. This will trigger a rise in price. As the price rises, the product will become a more lucrative thing to supply, as more profit can be made due to the rise in price, attracting other people to come and sell the product, and thus increasing competetion.
For the second part:
Loan capital is simply loans that the business has taken out to find the buying of fixed assets. Now, if you are a highly geared business, meaning that you have taken out loads of loans and are in big time debt, then you will be severely affected by a rise in interest rates, as you have a lot of borrowed money. Thus cumulatively, you will get a hell of a lot more debt. Now as we know, debt managment is a part of a business fixed costs, and thus will increase fixed costs.
Post by: nid404 on April 17, 2010, 04:25:30 pm
any idea?:
38 Which compounds would be formed in the reaction of ethene with aqueous bromine in the
presence of sodium chloride?
1 CH2ClCH2Cl
2 CH2BrCH2Cl
3 CH2BrCH2Br
the answer is 2&3
but wat if after ethene & bromine formed dibromoethane, the Cl in NaCl replaces one Br n then th next Br is replaces by NaCl as well (since we dont no how many NaCl(s) r present) wodnt we end up w/ CH2ClCH2Cl ?
y is tht rong?
I literally forgot abt this one...
In a few hours
Post by: sameee on April 17, 2010, 05:34:57 pm
any idea?:
38 Which compounds would be formed in the reaction of ethene with aqueous bromine in the
presence of sodium chloride?
1 CH2ClCH2Cl
2 CH2BrCH2Cl
3 CH2BrCH2Br
the answer is 2&3
but wat if after ethene & bromine formed dibromoethane, the Cl in NaCl replaces one Br n then th next Br is replaces by NaCl as well (since we dont no how many NaCl(s) r present) wodnt we end up w/ CH2ClCH2Cl ?
y is tht rong?
Hello SueT, well, with aqueous bromine, 2 products are formed, CH2BrCH2OH and CH2BrCH2Br, the later must be true, since its one of the choices given,no. 3. for number 2, the Cl will displace the OH in a nucleophilic substitution reaction., thus giving, CH2BrCH2Cl. No. one is NOT possible, since its a freeradicle sustitution reaction, which would have involved Cl2 gase,Not aqueous CL-, and in the Presence of UV light.
Post by: sweetie on April 18, 2010, 09:56:04 am
Reagents are used to detect the presence of a particular ion.....
So what they mean by precipitating V3+ ions is the already existing V3+ ions are being precipitated, they are dissolved prior to the addition...there's no change in conc/amount of V3+ ions, only the existing ions dissolved would be precipitated, this will not bring about a change in equilibrium
Thank You :-*
Post by: sweetie on April 18, 2010, 10:16:50 am
i need help in these que's plz :-\
Q3, 11 and 17
Post by: nid404 on April 18, 2010, 10:23:38 am
Al+--Al2+ +1820 2nd I.E
so Al---Al2+ +2397kj/mol
Co--Co+ +757
Co+--Co2+ +1640
so Co--Co2+ + 2397 kj/mol
So A
Post by: sweetie on April 18, 2010, 10:34:12 am
Post by: nid404 on April 18, 2010, 10:35:07 am
2HI(g)<-----> H2(g) + I2(g)
initial b 0 0
final b-x x x
total no of moles= 4
pressure = p
*pp=partial pressure
Kp= ppI2 XppH2/ pHI2
ppI2 and H2= x/4 Xp ( moles/total no of moles X total pressure)
ppHI= b-x/4 Xp
Kp= (xp/4)X (xp/4)
-------------
((b-x)p/4)2
=___x_2__
4(b – x)2
D
Post by: nid404 on April 18, 2010, 10:43:54 am
when a compound has no charge...
u equate the ox states to 0
A NH4Cl NH4 has ox state of +1 so Cl will be -1 ruled out
B NH4ClO3 +1 + (3x-2)[oxygen has state -2) + cl=0
Cl= +5 rule out
C NH4ClO4 +1 + (4X-2) + Cl=0
Cl=-7 here we got it :)
Post by: The SMA on April 19, 2010, 11:19:39 am
Q5 (i), Q8 and Q11 (ii)
Post by: nid404 on April 19, 2010, 11:30:23 am
in 7 minutes
thanks A.F
I'm trying to figure waves :-X :-[
Post by: sweetie on April 19, 2010, 01:29:43 pm
15) C
when a compound has no charge...
u equate the ox states to 0
A NH4Cl NH4 has ox state of +1 so Cl will be -1 ruled out
B NH4ClO3 +1 + (3x-2)[oxygen has state -2) + cl=0
Cl= +5 rule out
C NH4ClO4 +1 + (4X-2) + Cl=0
Cl=-7 here we got it :)
oops, i guess u xplained da wrong que., it waz q17!!!!!
Post by: sweetie on April 19, 2010, 01:34:20 pm
11)
2HI(g)<-----> H2(g) + I2(g)
initial b 0 0
final b-x x x
total no of moles= 4
pressure = p
*pp=partial pressure
Kp= ppI2 XppH2/ pHI2
ppI2 and H2= x/4 Xp ( moles/total no of moles X total pressure)
ppHI= b-x/4 Xp
Kp= (xp/4)X (xp/4)
-------------
((b-x)p/4)2
=___x_2__
4(b – x)2
D
but when i simplified the eqn. u got for Kp i didnt get the rite ans.
cud u plz solve it and send it to me??????
Post by: nid404 on April 19, 2010, 08:06:49 pm
but when i simplified the eqn. u got for Kp i didnt get the rite ans.
cud u plz solve it and send it to me??????
ok my bad...
that four kinda vanishes...ill do it agn..i must've made a mistake in a hurry
ill check
Post by: Metallicnak on April 22, 2010, 06:26:53 am
BIO!!!!!
Hey guys can someone explain to me the formation of the plant cell wall during plant cell cytokinesis ???, its annoying and my book doesnt explain it that well
Post by: Amr Fouad on April 22, 2010, 11:49:15 am
BIO!!!!!um sure nid can help. Shes our super duper bio geek :P lol
Hey guys can someone explain to me the formation of the plant cell wall during plant cell cytokinesis ???, its annoying and my book doesnt explain it that well
Post by: nid404 on April 22, 2010, 11:53:58 am
BIO!!!!!
Hey guys can someone explain to me the formation of the plant cell wall during plant cell cytokinesis ???, its annoying and my book doesnt explain it that well
Like what... :-\
Is this A2 ???
I'm really not getting you...can you show this to me in the syllabus
Post by: Metallicnak on April 22, 2010, 01:47:32 pm
Like what... :-\
Is this A2 ???
I'm really not getting you...can you show this to me in the syllabus
Nope it isnt A2, its in chapter 4 Biodiversity and natural resources pg-147 of the AS Bio textbook(black one) as for the syllabus (Topic 4 unit2) its a part of the 3rd and 4th points I gues :-\
Sorryzzzz to trouble u :-[ but for stem cells found in the embroyo it goes through continous divisions to maybe form a single blood cell which then cells divide to form range of blood cells until it loses its ability to further divide right ???
Post by: zb on April 22, 2010, 11:19:04 pm
Post by: T.Q on April 22, 2010, 11:46:00 pm
asalamoalaikum... I have a qn from edexcel AS physics... A person weighing 100 N stands on some bathroom scales in a lift. If the scales show a reading of 110 N ,which answer could describe the motion of the lift? A. moving downwards and decelerating B. Moving downwards with constant velocity C. Moving upwards and decelerating D. Moving upwards with a constant velocity thanks alot jaza kALLAH khairan :)wa alikom il salam
the answer is D
Post by: Metallicnak on April 23, 2010, 11:27:06 am
Nope it isnt A2, its in chapter 4 Biodiversity and natural resources pg-147 of the AS Bio textbook(black one) as for the syllabus (Topic 4 unit2) its a part of the 3rd and 4th points I gues :-\
Sorryzzzz to trouble u :-[ but for stem cells found in the embroyo it goes through continous divisions to maybe form a single blood cell which then cells divide to form range of blood cells until it loses its ability to further divide right ???
guys.... some help wuld be nice! >:( ........ and does any one hve the jan 2010 6B102 and 6B107
Post by: nid404 on April 23, 2010, 11:28:46 am
guys.... some help wuld be nice! >:( ........ and does any one hve the jan 2010 6B102 and 6B107
im sorry...that seems like edexcel...no wonder it's not in my textbook :-\
Post by: Metallicnak on April 23, 2010, 11:39:20 am
im sorry...that seems like edexcel...no wonder it's not in my textbook :-\
so all the edexcel bio guyz out there HELP! Plzzzz
Post by: zb on April 23, 2010, 02:01:40 pm
wa alikom il salamhow come???? Mark scheme says moving downwards and decelerating? The question is from jan 2010 unit 1 question 6 thanks
the answer is D
Post by: dazzlingleon93 on April 23, 2010, 06:02:44 pm
so if anyone did it>>>>>>do post it up here>>>>i would really appreciate it
thankssssss
Post by: sweetie on April 25, 2010, 07:35:27 pm
ok my bad...nid cud u plz show it again?????????
that four kinda vanishes...ill do it agn..i must've made a mistake in a hurry
ill check
Post by: nid404 on April 25, 2010, 08:02:41 pm
nid cud u plz show it again?????????
tom...i have to hurry to bed now..srry
tom definitely
Post by: sweetie on April 27, 2010, 09:22:48 pm
may02, P1 (CIE)
Q6,21,11
Post by: The SMA on April 28, 2010, 03:16:19 am
copy of 9701 As/A level Chemistry PastPapers book online
(the one with fully explained solution) preferably topic-by-topic.
Really wish to buy the book so it could aid me in my upcoming exams.
and By the way, i have chemistry pastpapers book actually,
but its a different syllabus code 9258 (Singapore's syllabus maybe)
n i thought that it would be an alien to CIE. does it do any good?
one more thing, guys, if u happens to have very useful chemistry revision
notes could u share them with me pleaaaase?
help me in here guys, will really appreciate it :D
Post by: nid404 on April 28, 2010, 09:38:11 am
more Que's in chem.
may02, P1 (CIE)
Q6,21,11
Q6) P1V1+P2V2= P3V3
he (1X2) + ne (2X1)= x X 3
x= 4/3
A
What you do is take a V3= 3dm3 (1dm3 of he and 2 dm3 of ne..since they are connected)
Q11) C
It will keep increasing as more products are formed...later, reactants act as a limiting agent...
If you are wondering why the curve can't plateau out, it is because no more substrate has been added to keep the rate constant....as the conc of substrate falls, rate of reaction falls
Q21) You already had 6 as soon as you figure the formula...right?
now when the haloalkane is either one of these C2H4Cl2 or C2H2Cl4 or C2H3Cl3, they could have isomers...
in C2H4Cl2 the Cl could be on each carbon or only on 1 carbon...2 possible structures
C2H2Cl4 the Cl could be 2 on each carbon or 3 on 1 and 1 on the other
C2H3Cl6 the Cl could be all 3 on one, or divide as 2 on 1 and 1 on the other
6+ the 3 possibilities = 9
C
Post by: ~ A.F ~ on April 28, 2010, 09:45:04 am
+rep. :)
Post by: nid404 on April 28, 2010, 09:49:25 am
Thank You :)
Post by: sweetie on April 28, 2010, 11:22:09 am
+rep
Post by: nid404 on April 28, 2010, 11:37:27 am
Thank You nid..
+rep
ur welcome :)
Post by: cashem'up on April 28, 2010, 01:19:01 pm
Post by: Saladin on April 28, 2010, 01:23:28 pm
Hope that helps.
Post by: nid404 on April 28, 2010, 01:26:35 pm
They won't ask you very complex stuff...the ones they give are usually easy to figure, just keep their structure in mind, and visualize the possibilities...always attempt these questions in the end, you get more time to draw and figure it out then
Post by: Sue T on April 29, 2010, 11:27:12 am
alpha particles have discreet energy values
beta have a continuous spectrum
(it ws an answer 2 a past paper question askin bout the diff between them)
Post by: Saladin on April 29, 2010, 12:03:45 pm
This is a comparison between the two:
Composition and Charge:
Alpha particles are basically helium nuclei composed of two neutrons and two protons. The protons give alpha particles a positive charge. Beta particles are fast moving electrons and are negatively charged. Gamma rays are a form of energy that is part of the electromagnetic spectrum. They are neutral.
Speed and Penetration:
Alpha particles travel at about 1/20th the speed of light and can easily be blocked by paper. Beta particles travel almost at the speed of light and can be blocked by an aluminium sheet. Gamma rays travels at the speed of light and can only be blocked by a few centimetres of lead.
Deflection in a magnetic field:
Alpha particles are heavy and deflect very little in a magnetic field. Beta particles are lighter and have the greatest deflection in a magnetic field. Gamma rays are neutral and so do not undergo any deflection.
Post by: sweetie on April 29, 2010, 11:51:28 pm
may09> Q18
Nov08. Q4
May08. Q31,22,16,14,12
Post by: ruby92 on May 03, 2010, 10:22:51 am
m/j 2006
15,12,17,22
o/n 2006
25, 27, 30,31,33,
Post by: T.Q on May 03, 2010, 09:34:14 pm
physics CIE paper 1
m/j 2006
15,12,17,22
o/n 2006
25, 27, 30,31,33,
m/j 2006
12. 4mX=3mv-2mv speed = v/4 answer A
15. answer A , 160=120+X X=40
17. answer is D , a=5 , 0=30^2 - 2x5xh
22. answer is B , area under graph = ( 0.5 x 0.01 x 500) + ( 0.02 x 500) +( 0.02 x 50 x 0.5)
Post by: T.Q on May 03, 2010, 09:54:40 pm
physics CIE paper 1
m/j 2006
15,12,17,22
o/n 2006
25, 27, 30,31,33,
o/n 2006
25. answer C , lamda=2pie, 1.5lamda=3pie
33. answer A , gradient=1/R
Post by: ruby92 on May 04, 2010, 01:12:26 pm
Post by: Sue T on May 05, 2010, 04:01:34 pm
Post by: nid404 on May 05, 2010, 04:14:58 pm
Post by: Sue T on May 05, 2010, 04:29:52 pm
Post by: ruby92 on May 05, 2010, 11:09:54 pm
in a question its given;
for an experiment to determine Kc 1.00 mol ethanoic acid 1 mol ethanol in the presence of 0.100 mol of H+ dissolved in 1 mol water.
where does the 0.100 mol H+ come in
Post by: moon on May 06, 2010, 02:11:42 am
Post by: halosh92 on May 06, 2010, 11:53:56 am
ijust dont get it.are there any rules for it???
Post by: nid404 on May 06, 2010, 12:58:02 pm
i need some help with 5 (b) pls (question attached)
I've answered this before...wait i'll get you the link
Post by: moon on May 06, 2010, 01:29:42 pm
please I need help in specimen 6BIO2 Q4c.nobody studies edexcel except me here ??? ???
Post by: nid404 on May 06, 2010, 01:38:21 pm
i need some help with 5 (b) pls (question attached)
there is a formula u need to know
phase difference=( 2pi/ lamda) X path difference
phase difference = pi [ for destructive interference]
lambda(wavelength) = 2pi/ pi X path difference.
path difference is S2M - S1M
find S2M using Pythagoras = root of 802 + 1002
=128
path difference= 128-100=28
wavelength= 2pi/pi X 28
=56cm
At f= 1KHz wavelength= 0.33m/ 33cm
At f=4kHz wavelength= 0..0825/8.25cm
wavelength changes from 33cm to 8.25cm
for minima...phase difference should be either one of them pi, 3pi,5pi,7pi [sub them in the eqn]
minima is observed when lambda= 56cm, 18.7cm, 11.2cm, 8cm
which are the 2 values between 33 and 8.25?? 18.7 and 11.2...so only 2 minimas
Post by: Dr.Black Knight on May 06, 2010, 01:38:47 pm
nobody studies edexcel except me here ??? ???I too do edexcel
Does anyone have the core practicals for bio 1 and 2 I'm doing the alternative to practicals!!1
And for phy6!!!
Post by: Sue T on May 07, 2010, 08:32:13 am
Post by: Freaked12 on May 07, 2010, 09:06:03 pm
Question 9
i did part 1...subtracting the area of rectangle from the area of curve
but part 2, about the volume etc
and part 3
Pleaseeee
Post by: Freaked12 on May 07, 2010, 09:06:41 pm
October November 2008Its pure maths paper 1
Question 9
i did part 1...subtracting the area of rectangle from the area of curve
but part 2, about the volume etc
and part 3
Pleaseeee
Post by: astarmathsandphysics on May 07, 2010, 09:49:29 pm
Post by: Freaked12 on May 07, 2010, 10:19:10 pm
Will do it tomorrow. Have been away for 2 days becos of a disk I had to recover.. Just going through all the probs I have to answer
alright then
but if your a tutor,you could have done it in minutes.
pLease :D
Post by: nid404 on May 08, 2010, 07:41:23 am
October November 2008
Question 9
i did part 1...subtracting the area of rectangle from the area of curve
but part 2, about the volume etc
and part 3
Pleaseeee
The volume obtained when the shaded region is rotated through
360 ° about the x-axis is given by
Volume of revolution of the curve , y = 2 - Volume of revolution of the curve
Now Volume of revolution of the curve y = 2 is given by
Volume of revolution=
=
Volume of revolution of the curve=
therefore volume of revolution=
=
=
=
=
=
Volume of the shaded region=
Next answer up in a while
Post by: nid404 on May 08, 2010, 08:11:00 am
ohk...check the pic to look how the tangents are
We next find the acute angle, between the two tangents.
The equation of the curve is
i.e
differentiating with respect to x
so
we know
Gradient of tangent at P
If the angle made by the tangent with the +ve direction of x axis is
Gradient of tangent at Q is given by
If the angle made by the tangent with the +ve direction of x axis is
Let the tangent to the curve at point P intersect the x axis at point S and the tangent at point Q intersect the x axis at the point T.
Let the two tangents intersect at the point R.
Consider
In
Now
so
i.e
so angle between the tangents =
== 56.3099° – 36.8699° = 19.44°
I feel so good to help....that satisfaction :)
Post by: Freaked12 on May 08, 2010, 06:49:28 pm
The volume obtained when the shaded region is rotated through
360 ° about the x-axis is given by
Volume of revolution of the curve , y = 2 - Volume of revolution of the curve
Now Volume of revolution of the curve y = 2 is given by
Volume of revolution=
==
Volume of revolution of the curve==
therefore volume of revolution=
=
=
=
=
=
Volume of the shaded region== 1.5\pi
Next answer up in a while
you just saved me 150 riyal i was about to pay to a tutor
God bless
Post by: nid404 on May 08, 2010, 06:53:10 pm
Good luck ;)
Post by: halosh92 on May 08, 2010, 09:14:13 pm
lol....Now I finally know how to use the latex thingy...cool
ohk...check the pic to look how the tangents are
We next find the acute angle, between the two tangents.
The equation of the curve is
i.e
differentiating with respect to x
so
we know
Gradient of tangent at P
If the angle made by the tangent with the +ve direction of x axis isthen
Gradient of tangent at Q is given by
If the angle made by the tangent with the +ve direction of x axis isthen
Let the tangent to the curve at point P intersect the x axis at point S and the tangent at point Q intersect the x axis at the point T.
Let the two tangents intersect at the point R.
Consider
In
Now
so
i.e
so angle between the tangents =
== 56.3099° – 36.8699° = 19.44°
I feel so good to help....that satisfaction :)
this is C2??
P.S nid ure awesome ;)
Post by: nid404 on May 09, 2010, 07:23:13 am
why thank you :)
Post by: ruby92 on May 10, 2010, 11:58:42 am
4 f (ii)
ally alcohol CH2=CHCH2OH
heated under reflux with acidified MnO4 -
according to the Ms the product is HO2CCO2H
what about the CH2OH part?
Post by: nid404 on May 10, 2010, 01:57:35 pm
the extreme left Carbon forms CO2 and the middle one forms CO2H.
Gettin it
Post by: ny on May 10, 2010, 03:51:29 pm
actually it was my mock exam question.
the question is:
the points A and B are such that the unit vector in the direction AB(from A to B) is 1/3i + pj +2/3k , where p is a negative constant.
i) find the value of p
then, the position vectors of A and B, relative to an origin O, are 9i +2j +qk and 12i -4j -5k respectively.
ii) find the value of q
thats all.thank you soo much.please reply asap..
Post by: ruby92 on May 10, 2010, 10:31:48 pm
Insert Quote
that is what gets converted to CO2H
the extreme left Carbon forms CO2 and the middle one forms CO2H.
Gettin it
sort of yes.but why does it form CO2?
Post by: nid404 on May 11, 2010, 04:39:00 am
You need to learn a few organic stuff the way it comes. Why? maybe in A2 :-\ I always ask questions like these. It's good to..but teachers don't like it :-\
Post by: Saladin on May 11, 2010, 04:41:52 am
That's a rule dear. Reaction with hot conc KMNO4 gives CO2, water, and acid. In this case dicarboxylic acid since there is also an OH group.
You need to learn a few organic stuff the way it comes. Why? maybe in A2 :-\ I always ask questions like these. It's good to..but teachers don't like it :-\
My sister often comes to me, why does acid + metal carbonate form salt +water + CO2. And I'm like, cuz it simply does, I can explain, but believe me, that wont make her happy. She will want to know more, and then get completely confused abt it!
Post by: Summer :] on May 11, 2010, 04:48:06 am
My sister often comes to me, why does acid + metal carbonate form salt +water + CO2. And I'm like, cuz it simply does, I can explain, but believe me, that wont make her happy. She will want to know more, and then get completely confused abt it!
Haha thats exactly how my sister thinks! and when she asks me further questions, she confuses me along with her
so thats i basically avoid her questions! or else ill get a U in chemistry
Post by: nid404 on May 11, 2010, 04:50:39 am
Maybe there's still some time before you know the "why" and "how"
Post by: Summer :] on May 11, 2010, 06:13:23 am
And I appreciate people who think like that. I always look for an explanation to things. I am very disappointed when I don't get my answer. I try every possible thing to find out. Use the net, look through books, ask people...
Maybe there's still some time before you know the "why" and "how"
that's true, i always think why does it happen as well..but at times it's best to avoid this question or else you'll be doomed like my sister.
sometimes there's the answer but its not required for our level of education, you'll learn it later in higher levels (thats what my teacher says ::) )
Post by: nid404 on May 11, 2010, 06:14:58 am
Post by: ruby92 on May 11, 2010, 11:38:50 am
That's a rule dear. Reaction with hot conc KMNO4 gives CO2, water, and acid. In this case dicarboxylic acid since there is also an OH group.lol. Thank You :)
You need to learn a few organic stuff the way it comes. Why? maybe in A2 :-\ I always ask questions like these. It's good to..but teachers don't like it :-\
Post by: cashem'up on May 11, 2010, 01:45:44 pm
And I appreciate people who think like that. I always look for an explanation to things. I am very disappointed when I don't get my answer. I try every possible thing to find out. Use the net, look through books, ask people...
Maybe there's still some time before you know the "why" and "how"
haha ;D ;D ;D totally agree so many ppl feel the same thing here....me too ...... u go to the teachers and ask dem WHY bcos u want to know wats the reason........the other day i still rememebr iasked my bio teacher how does the nucleus respond to detection of antigens on cell surface membrane.....she was like it happens... and i continued askin her like does the message reach automatically how does it instigate the nucleus(this sounds stupid... :P but realy i like to understand things rather than muggin it up.....lol )
;D ;D ;D
Post by: cashem'up on May 11, 2010, 01:49:38 pm
Posted by: nid404
Insert Quote
that is what gets converted to CO2H
the extreme left Carbon forms CO2 and the middle one forms CO2H.
Gettin it
sort of yes.but why does it form CO2?
i can give u slight more clarity on how it happens..... see basically the double bond breaks.... now mn04 is an oxidising agent so the CH2 is oxidised to CO2 now
for the right part if the carbon in compound is primary a COOH will form on full oxidation and aldehyde on partial
whereas if C is secondary ketone will form
hope it helped..... ;D ;D ;D
Post by: ruby92 on May 11, 2010, 05:59:58 pm
Thanks a lot :)
Post by: ruby92 on May 11, 2010, 06:01:40 pm
in an experiment to find the effect of temperature on rate of breakdown of H2O2 by catalase.
what can we take as the control?
Post by: cashem'up on May 11, 2010, 08:28:54 pm
yes definitely.
Thanks a lot :)
u welcome.... ;D ;D ;D
Post by: cashem'up on May 11, 2010, 08:33:58 pm
Bio related question.
in an experiment to find the effect of temperature on rate of breakdown of H2O2 by catalase.
what can we take as the control?
i am not sure but u could boil the catalase and then use it to prove that breakdown is ocuring due to catalase and not any other factors...........
Post by: pjb13 on May 12, 2010, 03:10:07 am
What is GDP/output gap...the diff between potential GDP and nominal or real GDP?
Need help abt the characteristics of the following regarding ....normal/abnormal profits in the short or long term, where does equilibrium occur on the graph in short term/long term, the position on the graph where profit maximization occurs if it does(MC=MR etc), when is it necessary to make a normal profit (in short/long run) :
1)Monopoly
2)Mono Competition
3)Perfect Competition
4)Oligopoly
Post by: Summer :] on May 12, 2010, 05:37:46 pm
Hahaha....ditto...exactly what my teachers say...sometimes I wonder whether they know it or not
i bet they dont :p (hi 5)! haha
Post by: Summer :] on May 12, 2010, 05:38:31 pm
Bio related question.
in an experiment to find the effect of temperature on rate of breakdown of H2O2 by catalase.
what can we take as the control?
control group is at room temperature 25 degrees celsius :)
Post by: halosh92 on May 12, 2010, 07:39:24 pm
p1
Q6
Q14
Q21
Post by: halosh92 on May 13, 2010, 08:55:08 am
physics cie 2009 nov
p1
Q6
Q14
Q21
can anyone solve this???
Post by: astarmathsandphysics on May 13, 2010, 11:22:25 am
Post by: astarmathsandphysics on May 13, 2010, 11:31:25 am
14.A
horizontal component at start=vertical component=v/sqrt2)
at top of flight vertical component of velocity is zero, so velocity=v/sqrt(2)
1/2m(v/sqrt2))^=1/2(1/2mv^2)
21.C energy=area under graph just a bit more than1/2*100*2*10^-3 ie 0.11
Post by: ruby92 on May 13, 2010, 06:17:18 pm
control group is at room temperature 25 degrees celsius :)
thnkx :)
Post by: halosh92 on May 13, 2010, 07:09:41 pm
june 2005 Q22
nov 2008 Q24
VERY URGENT
Post by: halosh92 on May 14, 2010, 09:05:27 am
physics cie paper 1 AS
june 2005 Q22
nov 2008 Q24
VERY URGENT
someone solve this plzzzzzzzzzz
with details
Post by: melony on May 14, 2010, 10:43:47 am
Quote
physics cie paper 1 AS
june 2005 Q22
nov 2008 Q24
VERY URGENT
As well as that please cud sum1 help me.. how do u determine the direction of the resultant of three coplanar forces. i.e mechanics paper 04/m/j/05 ???
thank yu!
Post by: Sue T on May 14, 2010, 02:03:17 pm
i havent done ny practical in school usin a c.r.o!
and also 'use calibration curves'
ny1 nos how 2 use both of them?
Post by: The SMA on May 16, 2010, 01:01:13 am
q 4, 9, 13, 15, 16, 22
Post by: vanibharutham on May 16, 2010, 09:06:51 pm
Post by: pjb13 on May 21, 2010, 09:01:33 pm
Post by: halosh92 on May 27, 2010, 04:18:07 pm
cie physics AS
nov 2001 p2
Q3c
could someone draw the arrows for me i want to check :)
thxx much!!!!!!!!!!!
Post by: nid404 on May 27, 2010, 05:06:12 pm
Post by: halosh92 on May 27, 2010, 05:13:29 pm
yup check the attachment
hey nid thankyou ;D
but i got the "R" wrong could u plzz explain why its in such a direction :)
thx
Post by: nid404 on May 27, 2010, 05:15:59 pm
Post by: halosh92 on May 27, 2010, 05:23:43 pm
hmm....well...it's reaction force...think abt mechanics now..lol...when u have a slope...and something is placed on it...visualize it's normal contact force...hope that helps
thx ;)
Post by: halosh92 on May 28, 2010, 10:30:29 am
nov 2009 p2
Q3Cii
why do we use the vertical component of velocity when we calculate momentum here why not the horizontal component??
Q4cii
part 2
Post by: nid404 on May 28, 2010, 11:44:55 am
x when weight is F+3.8N =17.8-14.2=3.6cm=0.036m
x when weight is 3.8N=16.3-14.2=2.1cm=0.021m
2 epe= 1/2 kx2 = 1/2 X 1.8 X 10^-2 X (change in x2)
=1/2 X 1.8 X10^-2 X (0.0362-0.0212)
=0.077 J
Post by: Ghost Of Highbury on May 28, 2010, 12:18:56 pm
i) The lengths of the chain are 0.3m and 0.4m and the distance between A and B is 0.5m. Given the tension in the longer chain is 36N, by resolving horizontally , find the tension in the shorter chain.
ii) By resolving vertically , find the mass of the lamp.
Please explain with A DIAGRAM!, thanks a lot! :D
Post by: halosh92 on May 28, 2010, 12:29:02 pm
it's falling vertically down...so you use the vertical component
x when weight is F+3.8N =17.8-14.2=3.6cm=0.036m
x when weight is 3.8N=16.3-14.2=2.1cm=0.021m
2 epe= 1/2 kx2 = 1/2 X 1.8 X 10^-2 X (change in x2)
=1/2 X 1.8 X10^-2 X (0.0362-0.0212)
=0.077 J
the answer am getting is 0.00000769
and for the extension why arent we taking only this extension:
x when weight is 3.8N=16.3-14.2=2.1cm=0.021m
as this is wat they only asked for...
Post by: nid404 on May 28, 2010, 12:36:02 pm
You the the angle between the two chains is 90. 0.32+ 0.42= 0.52 yup?
now find angles a and b
tan a= 0.4/0.3=53.13
b= 180-90-53.13=36.87
now sina/36 = sinb/ T is the shorter chain
T=27N in the shorter chain
Now resolving forces vertically
36sin36.87+27sin53.13= mg
0.6X36+ 0.8X27=mg
mg=45
m=4.5 kg
Post by: nid404 on May 28, 2010, 12:43:19 pm
the answer am getting is 0.00000769
and for the extension why arent we taking only this extension:
x when weight is 3.8N=16.3-14.2=2.1cm=0.021m
as this is wat they only asked for...
It says For the extension of the spring from a length of 16.3 cm to a length of 17.8 cm ... :-\
Post by: Ghost Of Highbury on May 28, 2010, 12:48:41 pm
Yup so here you go.
You the the angle between the two chains is 90. 0.32+ 0.42= 0.52 yup?
now find angles a and b
tan a= 0.4/0.3=53.13
b= 180-90-53.13=36.87
now sina/36 = sinb/ T is the shorter chain
T=27N in the shorter chain
Now resolving forces vertically
36sin36.87+27sin53.13= mg
0.6X36+ 0.8X27=mg
mg=45
m=4.5 kg
ok sry, i didnt put the q rite, it says by resolving horizontally show that the T in the shorter chain is 48N! not 27N
plus, the mass is 6kg :-/
Post by: nid404 on May 28, 2010, 12:56:23 pm
ok sry, i didnt put the q rite, it says by resolving horizontally show that the T in the shorter chain is 48N! not 27N
plus, the mass is 6kg :-/
ok then...refer to the same diagram
a=53.13
b=36.87
now 36cos36.87=Tcos53.13
T=48 N
now resolve vertically
36sin36.87+48sin53.13=mg
21.6 +38.4=mg
60=mg
m=6kg
Post by: Ghost Of Highbury on May 28, 2010, 12:57:37 pm
F = 27N ?
By the way, thanks for the other answers..! :)
Post by: nid404 on May 28, 2010, 12:58:44 pm
Okay, i tried that and i got it. But what puzzles me is the previous method u used, that is also a correct way to find the force rite?
F = 27N ?
By the way, thanks for the other answers..! :)
I am wondering...cause i used something similar in another question like this is the book...and got the right ans....I must check tho :-\
You're welcome ;)
Post by: The SMA on May 28, 2010, 02:34:32 pm
how do you arrange atoms/groups in an optical isomerism
for e.g (i) CH3COCOOH (ii) H3C-CBr(COOH)-CH2Br
if you could xplain in diagram it will be very much appreciated ^^
Post by: nid404 on May 28, 2010, 02:52:51 pm
So it's not possible in the first one.
Here's how the second one would look
Post by: The SMA on May 29, 2010, 07:40:45 am
Optical isomer are possible only in compounds containing a chiral carbon
So it's not possible in the first one.
Here's how the second one would look
nid is there a step/rule on arranging the atoms/groups? whether CH3- group or something else
should be on top the chiral Carbon atom [im taking the second problem H3C-CBr(COOH)-CH2Br as e.g ]
most of my answers for the question of this type does not seem to be similar to the Marking Scheme.
They put something different on top or at any other place. If i don't get the same arrangement as MS
will i be losing marks? :S
Post by: nid404 on May 29, 2010, 07:48:47 am
nid is there a step/rule on arranging the atoms/groups? whether CH3- group or something else
should be on top the chiral Carbon atom [im taking the second problem H3C-CBr(COOH)-CH2Br as e.g ]
most of my answers for the question of this type does not seem to be similar to the Marking Scheme.
They put something different on top or at any other place. If i don't get the same arrangement as MS
will i be losing marks? :S
I'm really not getting you :/ Rule in arranging? You simply reflect the compound...like you reflect something in a mirror.
the arrangement doesn't matter in this particular case...just that COOH and Br are side chains.
Post by: The SMA on May 29, 2010, 08:00:03 am
Post by: halosh92 on May 29, 2010, 05:35:04 pm
p2 june 2009
variant 1
Q2c, d
for 'c" shouldnt it be -1.6 ???
and for "d"......wats the formula for speed of separation and speed of approach? and do we take the signs into account?
Post by: Meticulous on May 29, 2010, 07:01:26 pm
Post by: halosh92 on May 29, 2010, 08:02:53 pm
Please post the question paper here halosh :)
sure
and could u do these as well plz same paper:
3bi .....why is the angle 90 ?
5b
7aii,7aiii
2nd variant:
Q7a
thankyouuuuuuu
Post by: Meticulous on May 29, 2010, 08:55:30 pm
physics cie AS
p2 june 2009
variant 1
Q2c, d
for 'c" shouldnt it be -1.6 ???
and for "d"......wats the formula for speed of separation and speed of approach? and do we take the signs into account?
c) it will move in the initial direction, which is positive! u see, the MAGNITUDE of force is the same in both, but the direction of force and impulse varies.
d) equation is: u1 - u2 = v2 - v1 = -(v1 -v2 )and yes you do take signs into account
Post by: halosh92 on May 29, 2010, 09:10:29 pm
c) it will move in the initial direction, which is positive! u see, the MAGNITUDE of force is the same in both, but the direction of force and impulse varies.
d) equation is: u1 - u2 = v2 - v1 = -(v1 -v2 )and yes you do take signs into account
thankyou ;D
and could u plz solve the rest?
:)
Post by: nid404 on May 30, 2010, 05:59:15 am
sure
and could u do these as well plz same paper:
3bi .....why is the angle 90 ?
5b
7aii,7aiii
3) b) max value of the function cosx is 1
cos 90=1
max turning effect when theta=90 :)
5b) there is a formula u need to know
phase difference=( 2pi/ lamda) X path difference
phase difference = pi [ for destructive interference]
lambda(wavelength) = 2pi/ pi X path difference.
path difference is S2M - S1M
find S2M using Pythagoras = root of 802 + 1002
=128
path difference= 128-100=28
wavelength= 2pi/pi X 28
=56cm
At f= 1KHz wavelength= 0.33m/ 33cm
At f=4kHz wavelength= 0..0825/8.25cm
wavelength changes from 33cm to 8.25cm
for minima...phase difference should be either one of them pi, 3pi,5pi,7pi [sub them in the eqn]
minima is observed when lambda= 56cm, 18.7cm, 11.2cm, 8cm
which are the 2 values between 33 and 8.25?? 18.7 and 11.2...so only 2 minimas
7)a)
ii) R between BX implies combined resistance of two parallel resistors in the loop BYCX = R/2
iii) AZ will be the combined resistance of all.
R in BY and CX are paralle...their combined value is R/2 this is in series with 2 more resistors.
So combined resistance = R/2 + 2R = 2.5R
Post by: halosh92 on May 30, 2010, 08:07:40 am
3) b) max value of the function cosx is 1
cos 90=1
max turning effect when theta=90 :)
5b) there is a formula u need to know
phase difference=( 2pi/ lamda) X path difference
phase difference = pi [ for destructive interference]
lambda(wavelength) = 2pi/ pi X path difference.
path difference is S2M - S1M
find S2M using Pythagoras = root of 802 + 1002
=128
path difference= 128-100=28
wavelength= 2pi/pi X 28
=56cm
At f= 1KHz wavelength= 0.33m/ 33cm
At f=4kHz wavelength= 0..0825/8.25cm
wavelength changes from 33cm to 8.25cm
for minima...phase difference should be either one of them pi, 3pi,5pi,7pi [sub them in the eqn]
minima is observed when lambda= 56cm, 18.7cm, 11.2cm, 8cm
which are the 2 values between 33 and 8.25?? 18.7 and 11.2...so only 2 minimas
7)a)
ii) R between BX implies combined resistance of two parallel resistors in the loop BYCX = R/2
iii) AZ will be the combined resistance of all.
R in BY and CX are paralle...their combined value is R/2 this is in series with 2 more resistors.
So combined resistance = R/2 + 2R = 2.5R
thankyou so much !!! but for the 5b........wat do we do if its constructive interference? and when do we exactly use that formula u gave, when we have to combine phase difference and path difference??
thxxx
and could u do the 2nd variant of the paper:
Q7a (with details) thxxxx alooot
Post by: nid404 on May 30, 2010, 08:11:23 am
thankyou so much !!! but for the 5b........wat do we do if its constructive interference? and when do we exactly use that formula u gave, when we have to combine phase difference and path difference??
thxxx
and could u do the 2nd variant of the paper:
Q7a (with details) thxxxx alooot
when it's constructive interference phase difference would be 0/2pi/4pi...etc.
We use the formula when you are given 2 of the values either lambda,path or phase difference and asked to find the other.
yup hold on for a while ;)
Post by: nid404 on May 30, 2010, 08:20:59 am
2nd variant:
Q7a
thankyouuuuuuu
7) a
Both are open. No current flows. so max resistance. R=
S1 open S2 closed. Current will pass only through the wire with S2. So resistance will be 2R (cause there are 2 resistors in series)
When both are close. R= combines resistance of 2R in parallel with each other...so combined resistance is R
Post by: halosh92 on May 30, 2010, 08:25:49 am
7) a
Both are open. No current flows. so max resistance. R=R=V/I I=0 anything divided by zero is not defined actually but ms says infinity...so we stick to that
S1 open S2 closed. Current will pass only through the wire with S2. So resistance will be 2R (cause there are 2 resistors in series)
When both are close. R= combines resistance of 2R in parallel with each other...so combined resistance is R
thankyou *bows* ;D ;D ;D
Post by: nid404 on May 30, 2010, 08:26:34 am
thankyou *bows* ;D ;D ;D
lol..not a problem :)
Post by: halosh92 on May 30, 2010, 09:07:19 am
Q2c
isnt change in momentum= m(v-u)
so isnt it supposed to be = 0.78(-9-4.2)
= -10.3 ??????????????
Post by: halosh92 on May 30, 2010, 01:22:44 pm
same paper 2nd variant
Q2c
isnt change in momentum= m(v-u)
so isnt it supposed to be = 0.78(-9-4.2)
= -10.3 ??????????????
could someone do this ? :S
Post by: halosh92 on May 30, 2010, 06:13:38 pm
Q2bi
isnt the answer 1:3
???
Post by: cooldude on May 30, 2010, 06:33:44 pm
june 2008
Q2bi
isnt the answer 1:3
???
maths, phy?, c1, c2, m1?
Post by: halosh92 on May 30, 2010, 07:04:47 pm
maths, phy?, c1, c2, m1?sorry ;D
physics cie
Post by: Meticulous on May 30, 2010, 07:09:31 pm
june 2008please post the q paper
Q2bi
isnt the answer 1:3
???
Post by: halosh92 on May 30, 2010, 07:16:04 pm
please post the q paperand Q4c as well
thx
Post by: Meticulous on May 30, 2010, 07:33:34 pm
Post by: halosh92 on May 30, 2010, 07:56:10 pm
june 2008 Q6b physics
with explanation plzzzzz
Post by: Meticulous on May 30, 2010, 08:20:22 pm
Post by: halosh92 on May 31, 2010, 08:36:21 am
Post by: nid404 on May 31, 2010, 10:48:51 am
could anyone solve this?
His morning = noon. Wake up A.F :P
I'll do it for ya :) Gimme 5 min :)
Post by: Deniz on May 31, 2010, 10:52:50 am
Post by: nid404 on May 31, 2010, 10:54:03 am
june 2008
Q2bi
isnt the answer 1:3
???
Initial momentum=0 so final momentum will also be equal to 0
2400XV-800v=0
opp directions.
2400V=800v
v/V=2400/800
v/V=3
Hope you got that now :)
Post by: nid404 on May 31, 2010, 10:55:02 am
can i ask sth? freeexampapers.com << this website is not opened how can i visit there. help pls :(
not opening? it's working fine here. If this doesn't work try xtremepapers.net
Post by: Deniz on May 31, 2010, 10:57:58 am
not opening? it's working fine here. If this doesn't work try xtremepapers.net
ok. it helped a lot ;)
Post by: nid404 on May 31, 2010, 10:58:55 am
and Q4c as well
thx
Now we know p=hdg
1.01 × 105 = h × 1.08 × 103 × 9.81
h=9.53m
they say it is assumed to be 10m
so % error= 10-9.53/10 X 100 = 4.7%
Post by: Nobody on May 31, 2010, 10:59:04 am
can i ask sth? freeexampapers.com << this website is not opened how can i visit there. help pls :(
no, don't use xtremepapers.net! i think it contains viruses.
Tell me what paper you want, I'll upload it here. :)
Post by: Deniz on May 31, 2010, 11:02:20 am
no, don't use xtremepapers.net! i think it contains viruses.
Tell me what paper you want, I'll upload it here. :)
hmm math additional paper 2 june. (2006-2007-2008-2009). i need these :)
Post by: Deniz on May 31, 2010, 11:15:23 am
no, don't use xtremepapers.net! i think it contains viruses.
Tell me what paper you want, I'll upload it here. :)
omg i believe i said wrong thing. im taking extended level. im so sorry for telling u the wrong papers :(
Post by: nid404 on May 31, 2010, 11:16:19 am
Post by: Deniz on May 31, 2010, 11:18:19 am
So please clarify which papers you want :)hey dont humiliate me :P
Post by: nid404 on May 31, 2010, 11:19:28 am
hey dont humiliate me :P
lol im not :P ill get you the papers...just be clear which one you want :P
Post by: Deniz on May 31, 2010, 11:22:02 am
lol im not :P ill get you the papers...just be clear which one you want :P
im really sorry my stupid friend made a comment insteead of me. the first one i want u to dowload was true. i want additional papers if u dont mind :) :)
Post by: nid404 on May 31, 2010, 11:22:46 am
im really sorry my stupid friend made a comment insteead of me. the first one i want u to dowload was true. i want additional papers if u dont mind :) :)
haha...nvm :P
Gimme 5 min :)
Post by: Deniz on May 31, 2010, 11:23:37 am
haha...nvm :Pwaiting 4 u ;)
Gimme 5 min :)
Post by: nid404 on May 31, 2010, 11:26:30 am
Post by: nid404 on May 31, 2010, 11:32:51 am
Post by: Deniz on May 31, 2010, 11:35:35 am
Here u go
thx !! 8)
Post by: nid404 on May 31, 2010, 11:45:26 am
Post by: Nobody on May 31, 2010, 12:19:31 pm
my pleasure :)
oh! nid... you always snatch my job! ;)
and Deniz, if you want other papers, post it in paper requests. :)
Post by: Meticulous on May 31, 2010, 12:26:10 pm
His morning = noon. Wake up A.F :P
Bleh :P
Post by: nid404 on May 31, 2010, 12:29:32 pm
Bleh :P
haww :(
Post by: Meticulous on May 31, 2010, 12:36:37 pm
haww :(
Shorry.ok..umm..sorry :P
Post by: nid404 on May 31, 2010, 12:38:02 pm
Shorry.ok..umm..sorry :P
wtv :P
Post by: Meticulous on May 31, 2010, 12:42:33 pm
wtv :P
haaaaaaww :( :P
Post by: nid404 on May 31, 2010, 12:46:04 pm
haaaaaaww :( :P
we can't do this here...so shush :P
Post by: halosh92 on May 31, 2010, 01:07:11 pm
Initial momentum=0 so final momentum will also be equal to 0
2400XV-800v=0
opp directions.
2400V=800v
v/V=2400/800
v/V=3
Hope you got that now :)
hey nid i rili dont get this if it is v/V shouldnt it be 800/2400 ??
thx ;)
Post by: nid404 on May 31, 2010, 01:10:07 pm
hey nid i rili dont get this if it is v/V shouldnt it be 800/2400 ??
thx ;)
ohkay wait
2400V-800v=0
2400V=800v
2400V/800=v
3V=v
3=v/V
does this help?
Post by: Ghost Of Highbury on May 31, 2010, 01:11:09 pm
The tension in one towrope is 1800N and in the other is 1650N. Given that the angles the reopes make with the direction of the motion are 20 degree and x degree respectively, find the value of x and Resistance to motion .
Answer --> As the angle is inversely proportional to the force, i used the inverse proportion concept to find the
x-angle. like this
1800 -> 20
1650 --> x
x = (20*1800)/1650 = 21.9 degrees (correct answer)
i used this x value to calculate the resistance and i got the correct answer.
---------------MY DOUBT----------------------------
i was wondering , is there any other way to find the x angle?
PS : Diagram attached.
Correct me if im wrong.
thank you.
Post by: halosh92 on May 31, 2010, 01:11:58 pm
ohkay wait
2400V-800v=0
2400V=800v
2400V/800=v
3V=v
3=v/V
does this help?
YES ALOOT
thx a bunch ;D ;D
Post by: halosh92 on May 31, 2010, 01:17:05 pm
sure A.F np.
june 2008 Q6b physics
with explanation plzzzzz
could u do this as well ?
Post by: nid404 on May 31, 2010, 01:19:51 pm
Barge of m=4000Kg , pulled in a straight line by two boats with an acceleration of 0.6m/s^2.
The tension in one towrope is 1800N and in the other is 1650N. Given that the angles the reopes make with the direction of the motion are 20 degree and x degree respectively, find the value of x and Resistance to motion .
Answer --> As the angle is inversely proportional to the force, i used the inverse proportion concept to find the
x-angle. like this
1800 -> 20
1650 --> x
x = (20*1800)/1650 = 21.9 degrees (correct answer)
i used this x value to calculate the resistance and i got the correct answer.
---------------MY DOUBT----------------------------
i was wondering , is there any other way to find the x angle?
PS : Diagram attached.
Correct me if im wrong.
thank you.
Yes aadi ...what you've done is not ideally the correct way.
Resolve the forces vertically. There is no vertical motion...so no resultant vertical force
1650 sinx= 1800sin20
Post by: nid404 on May 31, 2010, 01:21:46 pm
could u do this as well ?
yup :)
I've explained this a lot many times before :P It's long stuff...ill look for it :P
Post by: nid404 on May 31, 2010, 01:23:24 pm
1) When S1 is open, the circuit is not a closed one and hence not functional. Power will thus be 0
2) When only S3 is open, Current flows through A and wire with S2...power of each heating element is given as 1.5kW(stated in the question)...so in this case it is that of A. Current doesn't flow through B because it offers more resistance than wire with S2.
3)when all switches r closed...No current flows through B. You must know that any charge will take the path with least resistance....
So when S2 is closed, current flows through the wire with S2 since it offers a lesser resistance in comparison with wire with heating element B. So Power would be that of A nd C= 1.5+1.5=3kW
4)When only S1 is closed, Current flows through A and B...combined Resistance is 76.8ohms...I=3.125A..P=I2R =0.75kW
5)When only S2 is open, current flows through all the heating elements A, B and C.
A and B in series= 76.8ohms
With C in parallel
So combined R
1/R= 1/76.8+1/38.4
R=25.6
I=240/25.6=9.375
P=9.3752X25.6=2.25kW
Post by: halosh92 on May 31, 2010, 01:38:28 pm
here
1) When S1 is open, the circuit is not a closed one and hence not functional. Power will thus be 0
2) When only S3 is open, Current flows through A and wire with S2...power of each heating element is given as 1.5kW(stated in the question)...so in this case it is that of A. Current doesn't flow through B because it offers more resistance than wire with S2.
3)when all switches r closed...No current flows through B. You must know that any charge will take the path with least resistance....
So when S2 is closed, current flows through the wire with S2 since it offers a lesser resistance in comparison with wire with heating element B. So Power would be that of A nd C= 1.5+1.5=3kW
4)When only S1 is closed, Current flows through A and B...combined Resistance is 76.8ohms...I=3.125A..P=I2R =0.75kW
5)When only S2 is open, current flows through all the heating elements A, B and C.
A and B in series= 76.8ohms
With C in parallel
So combined R
1/R= 1/76.8+1/38.4
R=25.6
I=240/25.6=9.375
P=9.3752X25.6=2.25kW
thankyou :D
Post by: halosh92 on May 31, 2010, 03:01:55 pm
Q2dii
dont we have to subtract the forces? not add them?
Post by: Meticulous on May 31, 2010, 03:19:12 pm
f=force of boy, R=resultant, F=friction
therefore: f-F=R
f=F+R
got it?
Post by: halosh92 on May 31, 2010, 03:38:29 pm
No..you add them
f=force of boy, R=resultant, F=friction
therefore: f-F=R
f=F+R
got it?
not rili , dont we have to find the resultant in this case..i mean friction is 23 and the force of boy is 75 ..??
Post by: Meticulous on May 31, 2010, 03:54:21 pm
First:
resultant force= force by kid-friction
is that clear?
now add the resultant (mass x acceleration) to friction
Post by: halosh92 on May 31, 2010, 03:58:54 pm
Dont think of numbers
First:
resultant force= force by kid-friction
is that clear?
now add the resultant (mass x acceleration) to friction
YEPP :D
THANXXX
Post by: Meticulous on May 31, 2010, 04:02:09 pm
Post by: halosh92 on May 31, 2010, 05:26:01 pm
Q4d
Post by: Ghost Of Highbury on May 31, 2010, 07:44:22 pm
Yes aadi ...what you've done is not ideally the correct way.
Resolve the forces vertically. There is no vertical motion...so no resultant vertical force
1650 sinx= 1800sin20
wudnt u add the weight of the barge too to the downward force??
1650sinx + 40,000 = 1800sin20??
Post by: halosh92 on June 01, 2010, 08:41:36 am
nov 2007 physics
Q4d
could someone solve this!!!!!! ??? ??? ??? ???
Post by: cooldude on June 01, 2010, 08:55:47 am
wudnt u add the weight of the barge too to the downward force??
1650sinx + 40,000 = 1800sin20??
nope, nid's rite, cuz she has considered the forces acting on the barge, while the weight is the force of the gravity acting on the barge, the weight is balanced by the buoyance force acting on the barge by the water (obviously the boat and the barge will be in water :P ), just think as though the boat and the barge was on the ground, the normal force wud balance the weight of the barge and in this case the buoyance force does that
Post by: Ghost Of Highbury on June 01, 2010, 10:06:26 am
nope, nid's rite, cuz she has considered the forces acting on the barge, while the weight is the force of the gravity acting on the barge, the weight is balanced by the buoyance force acting on the barge by the water (obviously the boat and the barge will be in water :P ), just think as though the boat and the barge was on the ground, the normal force wud balance the weight of the barge and in this case the buoyance force does that
ok but many questions, like question 6...(same ex. 4A, q6) ...v had to take the weight into consideration!
is it something like, v dont consider the weight, wen two forces are acting on the object in the same direction.?? like here, two tugboats so no weight, but in q6...there are again 2 forces...push and pull...so while calculating the Normal contact force..y do we take the weight too??
Post by: cooldude on June 01, 2010, 05:55:31 pm
ok but many questions, like question 6...(same ex. 4A, q6) ...v had to take the weight into consideration!
is it something like, v dont consider the weight, wen two forces are acting on the object in the same direction.?? like here, two tugboats so no weight, but in q6...there are again 2 forces...push and pull...so while calculating the Normal contact force..y do we take the weight too??
yeah we gotta consider the weight in this, as the q is to find the normal force, thus we assume that the weight is not balanced by the component of the tension acting upwards, however in the q u asked previously we have to consider the weight and the buoyance force equal as the q has not been asked to consider the normal force.
Post by: sweetie on June 02, 2010, 10:43:06 pm
May07
Q26, 28
Post by: nid404 on June 03, 2010, 05:57:09 am
i need help in chem. ppr1( CIE)
May07
Q26, 28
26) You really have to draw and check. The OH should be tertiary(since it doesn't react with MnO4) Try making alcohols with the 5,6,7 and 8 carbons with a tertiary alcohol and a chiral carbon...
28) It has to be an aldehyde or a ketone to react with 2,4 DNP. so it's either B or C. Now to decolorise manganate ions, it has to form a carboxylic acid, which will happen only when an aldehyde is oxidised...so it's C.
Post by: thecandydoll on June 04, 2010, 07:03:34 am
Q5.
How do you get the answer explain?
Post by: nid404 on June 04, 2010, 10:49:10 am
CIE AS CHEM PAPER 1.
Q5.
How do you get the answer explain?
what year?
Post by: thecandydoll on June 04, 2010, 12:11:37 pm
what year?
2008 May/june sorry =)
Post by: nid404 on June 04, 2010, 01:00:36 pm
CIE AS CHEM PAPER 1.
Q5.
How do you get the answer explain?
It'll be C.
4 bond pairs. 109.5 degrees
Post by: sizbeauty on June 04, 2010, 01:13:05 pm
can u plz recommend me a gud buk for AS phsics which covers all conceptz n definitionz???plz i really need ur help!!!!
Post by: nid404 on June 04, 2010, 01:14:34 pm
http://www.amazon.co.uk/Bath-Advanced-Science-Physics-Second/dp/0174387318
Post by: sizbeauty on June 04, 2010, 08:20:52 pm
Post by: thecandydoll on June 06, 2010, 12:32:06 pm
M/J 2007-----Physics Q4d (i) and (ii)
And M/J/2007----PHYSICS q1 the whole thing!
I dont get it =(
thank youuuu!
Post by: nid404 on June 06, 2010, 01:48:15 pm
Anyone solve this for me ? :D
M/J 2007-----Physics Q4d (i) and (ii)
And M/J/2007----PHYSICS q1 the whole thing!
I dont get it =(
thank youuuu!
2 hrs
Post by: nid404 on June 06, 2010, 04:09:08 pm
Anyone solve this for me ? :D
M/J 2007-----Physics Q4d (i) and (ii)
And M/J/2007----PHYSICS q1 the whole thing!
I dont get it =(
thank youuuu!
4)d)
check the attachment
Post by: ruby92 on June 07, 2010, 02:24:24 pm
5cii ,dii
fo question 7 b iii
why would the lenght of between q and m be reduced should'nt it be increased?
Post by: nid404 on June 07, 2010, 03:07:33 pm
o/n 2005 phy paper 2
5cii ,dii
fo question 7 b iii
why would the lenght of between q and m be reduced should'nt it be increased?
5)c)ii)I=ka2
k=I/9
resultant amplitude=1
I = I/9
7)b)ii) R=rho l/ A
R directly proportional to the length
Post by: ruby92 on June 07, 2010, 04:31:24 pm
5)c)ii)I=ka2could you please explain these in a bit more detail ??? :-[
k=I/9
resultant amplitude=1
I = I/9
7)b)ii) R=rho l/ A
R directly proportional to the length
Post by: sweetie on June 07, 2010, 08:24:34 pm
Post by: thecandydoll on June 08, 2010, 08:09:55 am
Please explainnn Thankkk you so much!
Post by: moon on June 09, 2010, 07:07:16 pm
Post by: ruby92 on June 09, 2010, 08:36:55 pm
Post by: falafail on June 10, 2010, 04:14:10 am
and tbh, i find it unfair that only edexcel stuff get sticky threads? why can't edexcel people just post normal threads like the rest of us? >:[
but oh well, it's not like i'll be doing a levels anytime soon.
Post by: mdymmm on August 22, 2010, 10:19:49 pm
The diagram shows the graph of y=x^n where n is an integer.
Given that the curve passes between the points (2,200) and (2,2000), determine the value of n.
I just drew the curve roughly .. its not really accurate.
Thanks in advance :)
Post by: Saladin on August 22, 2010, 10:24:11 pm
hey every1 .. can any1 help me with this question ..
The diagram shows the graph of y=x^n where n is an integer.
Given that the curve passes between the points (2,200) and (2,2000), determine the value of n.
I just drew the curve roughly .. its not really accurate.
Thanks in advance :)
The value is 3, because it is a cubic curve.
Post by: S.M.A.T on August 23, 2010, 07:45:58 am
hey every1 .. can any1 help me with this question ..
The diagram shows the graph of y=x^n where n is an integer.
Given that the curve passes between the points (2,200) and (2,2000), determine the value of n.
I just drew the curve roughly .. its not really accurate.
Thanks in advance :)
how can a graph of y=x^n pass through (2,200) and (2,2000) at the same time ??? ???
Post by: Saladin on August 23, 2010, 11:59:10 am
how can a graph of y=x^n pass through (2,200) and (2,2000) at the same time ??? ???
I have no idea either, but that definitely looks like a cubic graph.
Post by: nid404 on August 23, 2010, 01:15:17 pm
Post by: Saladin on August 23, 2010, 01:52:06 pm
Post by: Ghost Of Highbury on August 25, 2010, 02:23:53 pm
i) change the width of each slit but the separation of the slit is same
ii) The separation of the slits is increased.
Post by: Saladin on August 26, 2010, 12:39:58 pm
How does the brightness of the spots on the screen (fringes) , the separation, and the number of fringes change as we
i) change the width of each slit but the separation of the slit is same
ii) The separation of the slits is increased.
I forgot about these....
The thing with exams is that once you're done you just forget what you did...
Post by: Alpha on August 26, 2010, 12:45:44 pm
how can a graph of y=x^n pass through (2,200) and (2,2000) at the same time ??? ???
The passes twice where x=2.
Post by: Saladin on August 26, 2010, 12:47:26 pm
How does the brightness of the spots on the screen (fringes) , the separation, and the number of fringes change as we
i) change the width of each slit but the separation of the slit is same
ii) The separation of the slits is increased.
This may be of some use.
Post by: S.M.A.T on August 26, 2010, 04:21:01 pm
The passes twice where x=2.
As far as i know a graph of y=x^n cannot pass through these points at the same time.
Post by: Alpha on August 26, 2010, 04:40:45 pm
As far as i know a graph of y=x^n cannot pass through these points at the same time.
Do you know the power (n)?
I know you're thinking about the arc shaped curve. That arc can make a more acute bend. Can it?
Post by: Ghost Of Highbury on August 26, 2010, 06:43:45 pm
for any n belongs to R...no matter how large the value of y is ...the graph wont ever become parallel to the y-axis.
Post by: S.M.A.T on August 26, 2010, 11:19:26 pm
Do you know the power (n)?
I know you're thinking about the arc shaped curve. That arc can make a more acute bend. Can it?
Oops :P i read the question wrong.It says the curve passes between the points (2,200) and (2,2000) not passes through (2,200) and (2,2000).
Post by: Saladin on August 26, 2010, 11:29:32 pm
Oops :P i read the question wrong.It says the curve passes between the points (2,200) and (2,2000) not passes through (2,200) and (2,2000).
That happens to me a lot, especially when I am sleepy! :D
Glad to see you so active Asif! :D
Post by: S.M.A.T on August 27, 2010, 09:55:19 am
hey every1 .. can any1 help me with this question ..
The diagram shows the graph of y=x^n where n is an integer.
Given that the curve passes between the points (2,200) and (2,2000), determine the value of n.
I just drew the curve roughly .. its not really accurate.
Thanks in advance :)
when x=2
y=2^n
The curve passes through a point with x-coordinate 2 and y-coordinate 200<y<2000
Therefore,
200<(2^n)<2000
(log(200)/log(2))<n<(log(2000)/log(2))
7.64<n<10.97
Since n is a integer,so n=8 or 9 or 10
Post by: Alpha on August 27, 2010, 02:37:30 pm
Oops :P i read the question wrong.It says the curve passes between the points (2,200) and (2,2000) not passes through (2,200) and (2,2000).
Oh okay. :)