Chemistry: Post your doubts here!

[donewithtime80]

why not SO4 2- is high?

 

[donewithtime80]

27 Which compound • is unaffected by hot alkaline potassium manganate(VII); • gives hydrogen when treated with sodium?

A (CH3)2CHCOCH3
B (CH3)3COH
C CH3CH2CH(OH)CH3
D CH3CO2CH(CH3)2

right answer is B ... but why not C? how is C affected bby KMnO4?

 

[donewithtime80]

how to go about questions like these?

 

[The Sarcastic Retard]

thank you ... i figured out my mistakes
anyway about the uses of different molecules and why it can be used for that purpose ... do you have a list or sth?

Which question are u talking about?

 

[The Sarcastic Retard]

12/o/n/13 - where is nucleophilic addition happening?

OH is a nucleophile, it will attack on aldehyde. You can compare reaction with HCN

 

[The Sarcastic Retard]

How to solve Q29?
http://papers.gceguide.com/A Levels/Chemistry (9701)/9701_w14_qp_13.pdf
http://papers.gceguide.com/A Levels/Chemistry (9701)/9701_w14_ms_13.pdf

For carbon atoms in plain, u have to see that connecting carbon is Sp2 hybridised, but all are Sp3 X is wrong.
For Y, You can clearly see, there is no possiblity of cis trans isomer there.

 

[The Sarcastic Retard]

View attachment 57487
pls help

R and n is constant.
P1V = T1
1*10^5 * V = 293
V = 2.93*10^-3
Total V = 4(V)
P2 * 4(V) = T2
V = A

 

[The Sarcastic Retard]

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9701 - Chemistry/9701_w06_qp_1.pdf

q:37 please
Answer is D

1) It has 2 ketone groups present in both product.
2) On double bond means only 1 product so 2 is wrong.
3) One product has both ketone (di-ketone), so 3 is wrong.

 

[The Sarcastic Retard]

27 Which compound • is unaffected by hot alkaline potassium manganate(VII); • gives hydrogen when treated with sodium?

A (CH3)2CHCOCH3
B (CH3)3COH
C CH3CH2CH(OH)CH3
D CH3CO2CH(CH3)2

right answer is B ... but why not C? how is C affected bby KMnO4?

B is tertiary alcohol. It cant be oxidised.
C is secondary, so it will be oxidised to ketone.
Both B and C will react with Na metal as OH group is present in both.

 

[The Sarcastic Retard]

View attachment 57488


why not SO4 2- is high?

From eqn 1 : We can get an idea that HSO4- will have lower concentration. And when SO4(2-) is formed from that, how u can say that it will be high?

 

[The Sarcastic Retard]

View attachment 57490

how to go about questions like these?

You can use trial and error method or go like this :~

 

[awesomaholic101]

Which question are u talking about?

Generally, i mean. They ask questions like why S02 is used as food preservative ... or why MgO is used for lining refractory kilns or sth ... so do you have like a list of things and it's uses that we can go through?

OH is a nucleophile, it will attack on aldehyde. You can compare reaction with HCN

the OH group in the ethanol ... i see. Thank you.

 

[The Sarcastic Retard]

Generally, i mean. They ask questions like why S02 is used as food preservative ... or why MgO is used for lining refractory kilns or sth ... so do you have like a list of things and it's uses that we can go through?


the OH group in the ethanol ... i see. Thank you.

No that was what my teacher made me learn in inorganic chemistry.
some things are asked from IGCSE level....

 

[awesomaholic101]

No that was what my teacher made me learn in inorganic chemistry.
some things are asked from IGCSE level....

ok ok

 

[The Sarcastic Retard]

ok ok

So prepared?

 

[ahmed butt]

Q30 ? i am getting 8 ketone functional group how to solve?
http://papers.gceguide.com/A Levels/Chemistry (9701)/9701_w14_qp_11.pdf
http://papers.gceguide.com/A Levels/Chemistry (9701)/9701_w14_ms_11.pdf

 

[donewithtime80]

1) It has 2 ketone groups present in both product.
2) On double bond means only 1 product so 2 is wrong.
3) One product has both ketone (di-ketone), so 3 is wrong.

how can 1 double bond mean only one product? doesn't each double bond breaking result in two products?

 

[The Sarcastic Retard]

how can 1 double bond mean only one product? doesn't each double bond breaking result in two products?

The product will be a straight chain

 

[The Sarcastic Retard]

Q30 ? i am getting 8 ketone functional group how to solve?
http://papers.gceguide.com/A Levels/Chemistry (9701)/9701_w14_qp_11.pdf
http://papers.gceguide.com/A Levels/Chemistry (9701)/9701_w14_ms_11.pdf

How 8?

 

[The Sarcastic Retard]

Anyone?