IIT JEE 2011 Problems Discuss

I have doubt in this:

20 Answers

11
Joydoot ghatak ·

bt why are allenes three dimensional structures.. any reason..??

71
Vivek @ Born this Way ·

Got it sir!

1
DAREDEVIL!!!!! ,,., ·

yaa i think it wasnt specified to consider anything......i too considered spring in stretched mode and got A as the answer...........

49
Subhomoy Bakshi ·

I got both right! :D

66
kaymant ·

The answer for the second one (phase diagram one) will be (B). The paragraph specified a sign convention to take position or momentum upwards as positive. So if starts from a positive position, its going to move down so the momentum will increase in the negative direction. This is happening in (B) and (C). However, owing to the resistance from water, the final position will be lower than the original one. This is happening in (B) only. Hence the answer.

1
seoni ·

hey sword

just giv it a thought,
if u consider upward motion first[as if spring was in stretched mode earlier],

u'll get a as ans..

1
swordfish ·

Vivek....D because the viscous force is more initially during the upward motion from the water....A cannot be an answer.

1
samagra Kr ·

i ve marked ABC for the organic one.its still doubtful......whats the correct ans ??

11
Joydoot ghatak ·

oh.. thats the reason.. i didn't know that.. :(

23
qwerty ·

for first B and C are correct. In D option, the left most and right most hydrogen will be n planes perpendicular to each other and not in the same plane

now i was confused for the first one , if you consider resonance , then according to the hybrid there is a partial double bond between C2-C3 , hence all atoms in 1 lie in same plane . But when i read the question again , they have mentioned "all possible conformations" , now if you dont take resonance into account then you can easily see that the bond between C2-C3 can be rotated, and then all atoms wont lie in a plane!
i was really confused at that point , and wrote ans as BC
but now i think jee will give abc as the answer .

btw what are the maximum marks that you guys have heard of ? and what are your marks [4]

71
Vivek @ Born this Way ·

Also, Why can't the answer be A here!

11
Joydoot ghatak ·

please dont ask me about my marks.. its way down my expectations.. :(

1
DAREDEVIL!!!!! ,,., ·

how many marks are u getting joydoot?

1
DAREDEVIL!!!!! ,,., ·

no the answer wont be abcd because the d option is allene which is a threedimensional system..

11
Joydoot ghatak ·

for second question, i too marked it as A. :(

11
Joydoot ghatak ·

shouldn't the first answer be A,B,C,D.
as sp and sp2 carbon atoms will lie in one plane.. and all the above carbon atoms are either sp or sp2 hybridised..

1
DAREDEVIL!!!!! ,,., ·

i too marked as A considering the downward to upward motion....

71
Vivek @ Born this Way ·

@Swodfish,

Shouldn't that ambiguity arise in question A or B instead of B or D?

71
Vivek @ Born this Way ·

Also, FIITJEE Solution mentions ONE QUESTION in MATHS as WRONG! (that from matrices)

1
swordfish ·

I left second question for that purpose. The answer can be B or D considering the initial motion of the block to start from the air downwards or from the water upwards resp. This one was ambiguous.

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