Lets Solve A's chem MCQ paper together.

[xhizors]

Hi Salam,, i was thinking how to get the maximum outcome by doing pastpapers and thought should try this.. Lets solve paper together live either on skype or on any live chat room
well skype would be more feasible if someone has other options plz do share.. plz do consider i am serious atleast we should try
my skype id muhammad.devdeen

 

[Mustehssun Iqbal]

I can volunteer but I am no expert in Chemistry, especially in MCQs. I get about 15 out of 30 MCQs correct in Chemistry

 

[smartangel]

yes please. chem mcq"s are crazy.. however, why skype? i mean solve the paper on your own and then post your difficulties here. and we all can help each other out.

 

[A7mAd-_-]

ok am here
and i am good in them
so how does it go ?

 

[shan5674]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s10_qp_11.pdf

Q-14,22,25,30, 35 can someone please explain

 

[MEGUSTA_xD]

I m in

 

[Amaryllis]

really useful thread ..i always find difficulties in solving MCQs chemistry

 

[CoNfUsEd1]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_11.pdf

Q-14,22,25,30, 35 can someone please explain

q.14: Dunno abt the HNO3 part but u just need to know that chloride forms a white ppt with AgNO3 which then dissolves in dilute NH3. the precipitate with bromide doesnt dissolve in dilute NH3 but dissolves in conc. NH3. the ppt with Iodide doesnt dissolve in conc. or dilute.. so the ans is A
q.22: conc. H2SO4 is a dehydrating agent. H2O is formed from the alcohols if they r dehydrated. the -OH part is taken from a certain Carbon atom in the alcohol, and the -H part is taken always taken from the Carbon atom adjacent to that previous Carbon atom; so that these two Carbon atoms then form an alkene double bond.... however, tertiary alcohols cannot be dehydrated since there is no -H attached to the Carbon atom adjacent to the Carbon of the -OH group..
q.25: the reaction is the reverse of esterification... in the hydrolysis, CH3COO-C3H7 splits to form CH3COO-Na and HO-C3H7
q.30: optical isomers require presence of a chiral carbon (carbon with all 4 different groups), cis trans isomers require an alkene bond with two different groups to each Carbon.
q.35:All 3 from sulfur, nitrogen and carbon react to form CO, NO, and SO2 respectively.. NO and SO3 are easily oxidised to form NO2 and SO3, but the CO bond is very strong (its the strongest chemical bond in the WORLD), so its not easily oxidised in air.

 

[smartangel]

i really need help with these questions.. 1,4,8,15,16,25,26,29,36.. in some of them i do have an explanation for my answer but apparently they:re wrong so if someone could please correct me!
in 16 isnt the major product of the electrolysis of brine, NaOH?
1n 25 (2.76 - 2.07)/2.76 x 100 gives us 75%. so why isnt B the answer?
in 29..why cant C be the right answer? im getting 3 Ch3 and 3 Ch2..
in 36..if we consider Sulfur then it doesnt form a basic hydride?
http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_11.pdf
i know these are quite a lot of questions but please do help me out because i think this is the 5th time im posting it in this forum but no one answered as yet ​

 

[smartangel]

COME ON GUYS. Help would be highly appreciated!!

 

[CoNfUsEd1]

i really need help with these questions.. 1,4,8,15,16,25,26,29,36.. in some of them i do have an explanation for my answer but apparently they:re wrong so if someone could please correct me!​

in 16 isnt the major product of the electrolysis of brine, NaOH?​

1n 25 (2.76 - 2.07)/2.76 x 100 gives us 75%. so why isnt B the answer?​

in 29..why cant C be the right answer? im getting 3 Ch3 and 3 Ch2..​

in 36..if we consider Sulfur then it doesnt form a basic hydride?​

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_11.pdf​

i know these are quite a lot of questions but please do help me out because i think this is the 5th time im posting it in this forum but no one answered as yet ​

nobody's answered cuz all these questions are HELL difficult
1. I2 sublimes and Br2 is liquid at rtp, so answer is either A or B.. sodium floats on water and Mg sinks, so ans is A
4. While measuring bond angles, double bonds are considered as single.. so think of the nitrogen atom having 2 bonds and a lone pair.. so the bond angle is roughly around 120 degrees (but not exact)
8. HSO3- acts as a base since it is a "proton acceptor" in both reactions.
15. use the masses to find out the no. of moles.... the equation is X(NO3)3 -----> 2NO2 + XO + 0.5O2
first find the total no. of moles of NO2 and O2, then no. moles of nitrate, then use the Mr of nitrate to deduce the metal.
16. a really annoying question =/ ..... no idea how but the report says that the following reaction takes place : Cl2 + NaOH ----> NaCl + NaClO
25. A very small mass of ethanol is boiled and refluxed, so it gets oxidised fully to ethanoic acid, not ethanal..
26. D is the ans since an H and an OH is added to the compound, so its the addition of water, and H2SO4 is a catalyst for these reactions..
29. yeah, there are 3CH3 and 3 CH2, but the question asks for the statement which is NOT correct, so D is da ans since the double bond on the left is not a cis-trans bond..
36. No idea, but the report says that only Nitrogen monoxide gets spontaneously oxidised in air, so A is the ans... If it was sulfur, then i guess the anhydride wouldnt have been basic..

 

[smartangel]

nobody's answered cuz all these questions are HELL difficult
1. I2 sublimes and Br2 is liquid at rtp, so answer is either A or B.. sodium floats on water and Mg sinks, so ans is A
4. While measuring bond angles, double bonds are considered as single.. so think of the nitrogen atom having 2 bonds and a lone pair.. so the bond angle is roughly around 120 degrees (but not exact)
8. HSO3- acts as a base since it is a "proton acceptor" in both reactions.
15. use the masses to find out the no. of moles.... the equation is X(NO3)3 -----> 2NO2 + XO + 0.5O2
first find the total no. of moles of NO2 and O2, then no. moles of nitrate, then use the Mr of nitrate to deduce the metal.
16. a really annoying question =/ ..... no idea how but the report says that the following reaction takes place : Cl2 + NaOH ----> NaCl + NaClO
25. A very small mass of ethanol is boiled and refluxed, so it gets oxidised fully to ethanoic acid, not ethanal..
26. D is the ans since an H and an OH is added to the compound, so its the addition of water, and H2SO4 is a catalyst for these reactions..
29. yeah, there are 3CH3 and 3 CH2, but the question asks for the statement which is NOT correct, so D is da ans since the double bond on the left is not a cis-trans bond..
36. No idea, but the report says that only Nitrogen monoxide gets spontaneously oxidised in air, so A is the ans... If it was sulfur, then i guess the anhydride wouldnt have been basic..

THANK YOU SO MUCH !! im so grateful to you! however, i really dont understand 1..could you plz explain it a bit more? and also 25..

 

[CoNfUsEd1]

In 1. sorry, i mean't the ans is B...
the first row of the table shows that melting point of X is lower than rtp (room temp & pressure) while the boiling point is greater than rtp. so X must be a liquid at rtp. We r supposed to remember the fact that Bromine is a liquid while iodine is a solid at rtp. so the ans is either A or B. next, we are supposed to remember that Sodium is a light metal and has lesser density than water, so it'll float on water. On the other hand, Magnesiun has a higher density than water (we are supposed to memorize all this). So ans is B
In 25. You are supposed to remember the fact that when primary alcohols are lightly oxidised, they form aldehydes. But if you strongly oxidise them, they form carboxylic acid.
2.76 g of ethanol is used, so its (2.76/46)=0.06 moles.. efficiency is 75%, so 0.75*0.06=0.045 moles of alcohol will be oxidised, and 0.045 moles of acid will be formed. Mr of ethanoic acid is 60, so mass of ethanoic acid formed is 60*0.045=2.70 g ....... So C is da ans!

 

[wajji345]

I can volunteer but I am no expert in Chemistry, especially in MCQs. I get about 15 out of 30 MCQs correct in Chemistry

SAME here :/

 

[smartangel]

In 1. sorry, i mean't the ans is B...
the first row of the table shows that melting point of X is lower than rtp (room temp & pressure) while the boiling point is greater than rtp. so X must be a liquid at rtp. We r supposed to remember the fact that Bromine is a liquid while iodine is a solid at rtp. so the ans is either A or B. next, we are supposed to remember that Sodium is a light metal and has lesser density than water, so it'll float on water. On the other hand, Magnesiun has a higher density than water (we are supposed to memorize all this). So ans is B
In 25. You are supposed to remember the fact that when primary alcohols are lightly oxidised, they form aldehydes. But if you strongly oxidise them, they form carboxylic acid.
2.76 g of ethanol is used, so its (2.76/46)=0.06 moles.. efficiency is 75%, so 0.75*0.06=0.045 moles of alcohol will be oxidised, and 0.045 moles of acid will be formed. Mr of ethanoic acid is 60, so mass of ethanoic acid formed is 60*0.045=2.70 g ....... So C is da ans!

thanks a million!

 

[ismailmz]

Hi Salam,, i was thinking how to get the maximum outcome by doing pastpapers and thought should try this.. Lets solve paper together live either on skype or on any live chat room
well skype would be more feasible if someone has other options plz do share.. plz do consider i am serious atleast we should try
my skype id muhammad.devdeen

sounds gr8 buddy heres my id skype :- ismailm.z

 

[saudha]

i love this idea....

 

[panda222]

i really need help with these questions.. 1,4,8,15,16,25,26,29,36.. in some of them i do have an explanation for my answer but apparently they:re wrong so if someone could please correct me!​

in 16 isnt the major product of the electrolysis of brine, NaOH?​

1n 25 (2.76 - 2.07)/2.76 x 100 gives us 75%. so why isnt B the answer?​

in 29..why cant C be the right answer? im getting 3 Ch3 and 3 Ch2..​

in 36..if we consider Sulfur then it doesnt form a basic hydride?​

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_11.pdf​

i know these are quite a lot of questions but please do help me out because i think this is the 5th time im posting it in this forum but no one answered as yet ​

Regarding Question 16

You are right on that Sodium hydroxide IS the main product. Howver, Don't forget that Cl2 and H2 are also given out at the anodes and cathodes respectively. Instead of just throwing the two gases away they are used. H2 can be used in the Haber process. Cl2 can be used in manufacture of paper and other stuff too. As a result, the two gases are considered products of the Electrolysis of Brine.

Hence, the answer is A. It's not B or C because the diaphragm cell prevents Cl- ions to cross the membrane and react with OH- ions to give Sodium Cholorate (NaClO). It's not D because Sodium Hydroxide is the main product and not "among the main products" as the question puts it.

 

[xhizors]

Salam guys

ok you are all welcome
a note to people:"we could solve them and ask problems here" alike
this is a good idea but the problem 1) when u do all ur q's chck ans some get wrongs u think about them and post it on xp
than after sometime u get those ans--> problems from this a) u get late ans, b) u most of the time forget the ques c) even this happens to me i dont like to ans 10 20 q's of other people at same instance u know laziness lol


Sols we must all solve 1 single paper at a time
with many brains the results,
we could master the mcq paper atleat five-ten mcq's paper could lead us an A grade
Ways to achieve
1) add me muhammad.devdeen or pm me ur skype id
2) we will set time to solve any 1 paper
3) we will inshallah solve more than 2 papers a day


Lets roll in and make our way to Distinctions
May Allah(swt) help us, strengthen us and make our ways easy
Jazakallah.

p.s.
a-(Inshallah i will post time for our first paper by today)
b-(anyone can join)
c-(plz geniuses help us)

 

[smzimran]

AOA,
Ah....
People, Your efforts remind me of last year when i was preparing for AS MCQ paper!
I was never scared of them so much, though
Managed to obtain an A in the end!
And I would have loved to answer your MCQ doubts had I got some spare time, believe me A2 is a killer !!!
Inshhallah, we will all get what we deserve from our hard work, may the almighty Allah reward us!
AMEEN