IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => Subject Doubts => GCE O - Level => Sciences => Topic started by: nox_fjmoony on May 28, 2009, 07:54:35 pm
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Um yeah, I was doing this paper and got stuck in questions:
19, 21, 22, 25, 26, 33, 36, 37 and 38.
Would really appreciate it if someone could help me out. Thanks in advance.
~Nox
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hey,the attachment wont open...can u tell which year they are from alongwith the syllabus code(it's 5070,i think)...
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sure mate. Its the o/n session, chemistry..code is 5070. Paper 1.
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19-the ans is 40 tonnes since of u look closely,2 mol of NH3 give 1 mol of ammonium nitrate. 17 tonnes makes 1 mol of ammonia,so 0.5 mol of ammonium nitrate will be there. mass=mol. x Mr ,so 0.5 x 80= 40 tonnes.
21.increasing pressure. reaction would move in the 4ward direction since the ratio of volumes is 4:2,more ammonia would be obtained and by increasing pressure, the frequency of effective collisions would also increase,thus the rate will be higher.
22.lowering the temp...slope of exp.2 is not as steep as 1. change in type or amount of catalyst is pointless since catalysts are not used up. B would give a smaller volume of oxygen.
25. A is the correct option.it is a neutralisation reaction and neutralisation AND precipitation reactions are non-redox
26.C. magnesium sulphate would form which is soluble.
33. C. silica is a non-metal,so its oxide will be acidic. no redox occurs since its oxidation state remains +4.
36. D. from acids,we always take away -OH and from alcohols we take H. cut these radicals from both sides of the monomers and u'll see.
37. i'm not sure,but i think it is ammonia. hydrogen does react. water also does,as in making alcohols,and bromine also reacts as in testing for unsaturation.
38. A. this is a fact. u'll know better if u've studied biology.
hope this helps :)
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Hey man, thanks a LOT. Thanks SO MUCH!!
I really appreciate it. ^_^
You don't know how much you've helped me. Thankyou. Thankyou very very much.
;D
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Hey man, thanks a LOT. Thanks SO MUCH!!
I really appreciate it. ^_^
You don't know how much you've helped me. Thankyou. Thankyou very very much.
;D
hey no problem ;) i love helping out...lets hope the exam tomorrow is easy ::)
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hey dude, lets hope so. So you're giving O-levels too?
I love helping out too..only this time, I needed some helping out..lol
But , I need some help again.
Its the first question in mj-08, p-1
I kinda suck at mcq's..but I won't in the exam, because I will give it my best shot.
Thanks again.
:D
Also if you have any problems, I'm here to help (if you need any that is) ;)
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yep,i'm giving o'levels too...i also suck at mcqs...its strange,u think u're doing everything right,but u're not...anyways,no.1 of m/j 08?
let me see....it is D because air has 79% nitrogen...it cannot be hydrogen peroxide since it would not leave the flask unless decomposed...not hydrogen because it is not a product of decomposition as shown by the equation...it cannot be water vapour because it would be present all the time cuz oxygen is collected over water,and the question asks why only the first FEW are rejected...the flask initially had air,most of which was nitrogen and this collected in the tube alongwith the oxygen.
i need help in biology...i really suck at it AND i hate it :-[ physics is also difficult but manageable...anyways,good luck...
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hey cool, that's what I thought too.
Anyhoo, I could help in bio and physics..I think. Ask away.
:D
Thanks and best of luck to you too.
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hey cool, that's what I thought too.
Anyhoo, I could help in bio and physics..I think. Ask away.
:D
Thanks and best of luck to you too.
ok i'll ask once i'm done with chem :) can't wait for 8th june :o
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I can't wait for the 12th..my exam finishes then. I have environmental management, you see.
Hey you got msn or sth? I wouldn't mind discussing chemistry mcq stuff live. What say you?
Ofcourse, its your wish, but if you agree then you can message me your id, or I could mine.
:D
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I can't wait for the 12th..my exam finishes then. I have environmental management, you see.
Hey you got msn or sth? I wouldn't mind discussing chemistry mcq stuff live. What say you?
Ofcourse, its your wish, but if you agree then you can message me your id, or I could mine.
:D
sry but i dont use msn anymore...no time...but i can help on the forum
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Well, cool enough. I don't use it much either. :D yeah, I posted another question. You can help me out on those. To tell you the truth, after your explanations, I'm finding it much easier to solve those mcq's. Thanks a lot. By the way, I'm Mony and I'm from Bangladesh. What about ya? ^_^
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Give me the answers for Q. 14 and 39, explain how u get them. 2008 o/n PI pls............... hekp
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14. write the balanced equation for the reaction...u'll notice that 1 mol of H2SO4 needs 2 mol for neutralisation,so D is the answer...
39. C is the answer. increase in nitrate conc. causes increase in growth of algae on the surface of water...this blocks sunlight so the water vegetation cannot photosynthesise without sunlight, furthermore,algae also cause loss in oxygen volume reaching the water plants,so they die...
hope this helps..i'm in a hurry
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wow thats gr8...i'm from pakistan,but i'll prefer to stay anonymous...i have my reasons...i'll just get to ur questions right now...
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Oh ok then, stay that way. :D
But you've been great. Thanks. You don't have to solve them now, because I'm going to bed soon, so won't be of much use. Thanks any way.
Actually I kinda like to stay anonymous, only I like to give my name and country to friendly folks. Anyhoo, best of luck mate and regards,
~Nox
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NOOO ...dont go now...do check out the reply i sent there!!! VERY USEFUL LINK!!!
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hey, Abc dude, how did your exam go?
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ummm....well i did my best...i found paper 1 easy but paper 2 had toooo much of organics and fertilisers,didn't it? but it went well overall...how abt u?