chem mcq...

[girlscampisra]

9?

 

[aquariangurl]

A & C
I THINK, not sure =/

 

[hassam]

 

[girlscampisra]

Ca ions wont accept H+ ions so how'll it react with acid!

 

[xHazeMx]

1st question : there are 7 chiral centres after reacting with LiALH4

2nd question : 1 and 2 because Ca+ doesnt react with H+ as girlscampisra said

 

[xHazeMx]

it is commonly known that acids are proton donors. the element reacting with acids should accept H+ ions from the acid which is not possible because Ca2+ and H+ are having the same charge

 

[girlscampisra]

how 7 chiral centres xHazeMx?

 

[xHazeMx]

how 7 chiral centres xHazeMx?

there are 6 chiral carbons present already without reacting with LiALH4. now if u look to the carbonyl group on the right side, carbonyl group get reduced to CHOH after reacting with LIALH4 and that makes an extra chiral carbon as it is bonded to four different groups

 

[girlscampisra]

there are 6 present already, and 2 carbonyl groups :s .. that makes 8 chiral carbon but as its not given in the option, i guess it'll reduce c=c too and in total there will be 9 chiral centres..

 

[girlscampisra]

see there are 2 C=O bonds..

 

[xHazeMx]

see there are 2 C=O bonds..

oh yeah sorry the image wasnt clear i thought there was 3 C==C .. i can see now 3 carbonyl groups and 6 present already so that will make 9

 

[MHHaider707]

1st question : there are 7 chiral centres after reacting with LiALH4

2nd question : 1 and 2 because Ca+ doesnt react with H+ as girlscampisra said

i think there will be 09 chiral Carbons coz there are three carbonyl groups and all will then give chiral C!!!

Right???

 

[xHazeMx]

1st question : there are 7 chiral centres after reacting with LiALH4

2nd question : 1 and 2 because Ca+ doesnt react with H+ as girlscampisra said

i think there will be 09 chiral Carbons coz there are three carbonyl groups and all will then give chiral C!!!

Right???

yeah correct the image wasnt clear so i thought there is 1 carbonyl group only the right answer is 9

 

[MHHaider707]

This MCQ was removed from the examination, right?
I read something on the ER, saying the statistics were unsatisfactory so it was removed.

And I also have another difficult MCQ (well, I think it is).

http://www.xtremepapers.me/CIE/Internat ... 4_qp_1.pdf

Question 31.

I reaaally don't get it at all. I'd be grateful if someone could explain it!

Answer is D . . . use Hes's law to do this question!!!

 

[MHHaider707]

is it C????

 

[girlscampisra]

no its D!

 

[alisha]

which year Alisha?

sorry typin error- may june 2006

 

[sweetiepie]

can any 1 explain me m/j 2006 Q.1 n more these type of questions???

 

[Feelguud77]

This MCQ was removed from the examination, right?
I read something on the ER, saying the statistics were unsatisfactory so it was removed.

And I also have another difficult MCQ (well, I think it is).

http://www.xtremepapers.me/CIE/Internat ... 4_qp_1.pdf

Question 31.

I reaaally don't get it at all. I'd be grateful if someone could explain it!

Answer is D . . . use Hes's law to do this question!!!

Spot on.

 

[xHazeMx]

can any 1 explain me m/j 2006 Q.1 n more these type of questions???

answer is D
N2O4(g) + 2NaOH(aq) → NaNO3(aq) + NaNO2(aq) + H2O(l)
use the formula C=n/v , N2O4 has 0.02 moles so NaOH will have twice that moles ( 0.04 moles ). now u have moles and concentration, find the volume which will be 80 cm^3

i hope everything is clear now