Chemistry: Post your doubts here!

[♣♠ Magnanimous ♣♠]

Won't it be x2= 4 (1-x)^2 -> x= 2(1-x) -> x= 2-2x -> 3x=2 -> x=2/3?

wah... thanks

 

[Suchal Riaz]

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question 23:
it means that the number of moles of ethene are 1/2 of total moles of products. it means that there are two moles of ethene, one mole of methane and one mole of propane.
total number of carbon=2 from each ethene, one from methane and three from propane/ 4+1+3=8

 

[Metanoia]

i am working on it Metanoia
i had to erase some answer because you had already answered them. please tell me which one you are doing so i do other queries instead.

Maybe we can quote and "click reply" immediately.

And then take your time to add the answers by editing the posts.

If it turns out we are repeating answers even after that, just leave them posted. Sometimes, it might be good to have differing approaches to the same questions.

Quite a few questions are repeated, so I just copied and paste what I type just a day or two ago.

Anyway, I will be here for just only a while longer .

 

[Suchal Riaz]

thats they way i am doing. adding each question one by one. but instead on new post because the answer won't get notification when i add new answer to the same post.

Maybe we can quote and "click reply" immediately.

And then take your time to add the answers by editing the posts.

If it turns out we are repeating answers even after that, just leave them posted. Sometimes, it might be good to have differing approaches to the same questions.

 

[ZaqZainab]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w04_qp_1.pdf
Q28

 

[Suchal Riaz]

Maybe we can quote and "click reply" immediately.

And then take your time to add the answers by editing the posts.

If it turns out we are repeating answers even after that, just leave them posted. Sometimes, it might be good to have differing approaches to the same questions.

Quite a few questions are repeated, so I just copied and paste what I type just a day or two ago.

Anyway, I will be here for just only a while longer .

you can take rest. i will handle these childish questions

 

[_Ahmad]

The part on the OH being added or the number of rings?

Both.

 

[Suchal Riaz]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w04_qp_1.pdf
Q28

the double bond can form between the carbon on which OH is atached and any adjacent carbon.
in (a) and (d) only one product as there is only one adjacent carbon to carbon on which OH is attached
in (b) if the double bond is formed between the 3rd and 2nd carbon then it will have 2 cis-trnas isomers. total 3 products.
in (c) again one product because both products will be same as the molecule is symetrical.

 

[Metanoia]

Sir can you please elaborate Q20

The 2 OH is added with cold dilute KMno4
The red circles are the 2 6-membered ring after hot KMno4 breaks the double bond.

 

[Metanoia]

thats they way i am doing. adding each question one by one. but instead on new post because the answer won't get notification when i add new answer to the same post.

I feel it doesn't matter, since they asked the questions, they should know to check back for the updated answers. But its up to you, whichever is comfortable.

 

[Rockstar RK]

Q8) Use of the Data Booklet is relevant to this question.

The approximate percentage composition of the atmosphere on four different planets is given in
the table below.

The density of a gas may be defined as the mass of 1 dm3
of the gas measured at s.t.p.

Which mixture of gases has the greatest density?


planet major gases / % by number of molecules
A Jupiter H2 89.8, He 10.2
B Neptune H2 80.0, He 19.0, CH4 1.0
C Saturn H2 96.3, He 3.25, CH4 0.45
D Uranus H2 82.5, He 15.2, CH4 2.3

 

[Metanoia]

Q8) Use of the Data Booklet is relevant to this question.

The approximate percentage composition of the atmosphere on four different planets is given in
the table below.

The density of a gas may be defined as the mass of 1 dm3
of the gas measured at s.t.p.

Which mixture of gases has the greatest density?


planet major gases / % by number of molecules
A Jupiter H2 89.8, He 10.2
B Neptune H2 80.0, He 19.0, CH4 1.0
C Saturn H2 96.3, He 3.25, CH4 0.45
D Uranus H2 82.5, He 15.2, CH4 2.3

I'll update this in a while

 

[Suchal Riaz]

Q8) Use of the Data Booklet is relevant to this question.

The approximate percentage composition of the atmosphere on four different planets is given in
the table below.

The density of a gas may be defined as the mass of 1 dm3
of the gas measured at s.t.p.

Which mixture of gases has the greatest density?


planet major gases / % by number of molecules
A Jupiter H2 89.8, He 10.2
B Neptune H2 80.0, He 19.0, CH4 1.0
C Saturn H2 96.3, He 3.25, CH4 0.45
D Uranus H2 82.5, He 15.2, CH4 2.3

the dense gas have heavier Mr.
to overall Mr of "D" is higher. you can calculate it like this:
[82.3%(2)+15.2%(4)+2.3%(16) ]/100=2.62
the average Mr of all others is less. you can check it.

 

[Suchal Riaz]

I'll update this in a while

done

 

[RHB :3]

Ok Last hours left
Can anyone tell me what to study now
I am confused :/

 

[Suchal Riaz]

I'll update this in a while

okay handle the queries for half hour. i will do my own papers during that time. thanks.

 

[Metanoia]

done

ok.

 

[♣♠ Magnanimous ♣♠]

Ok Last hours left
Can anyone tell me what to study now
I am confused :/

what? didn't you study till now

 

[Suchal Riaz]

Ok Last hours left
Can anyone tell me what to study now
I am confused :/

sorry to be rude but all you can do is pray and see the worked solutions of some difficult papers on this thread. so back a few pages and see the questions and their answers.

 

[Suchal Riaz]

what? didn't you study till now

As level is too easy to study. i ahev four papers printed. i haven't done any of them until now.