1

### AIPMT 2006

Which of the following is not chiral?
A
2-Hydroxypropanoic acid
B
2-Butanol
C
2,3-Dibromopentane
D
3-Bromopentane

## Explanation

Due to absence of asymmetric carbon atom.
2

### AIPMT 2004

Which of the following is least reactive in a nucleophilic sibstitution reaction?
A
(CH3)3C $-$ Cl
B
CH2$=$CHCl
C
CH3CH2Cl
D
CH2$=$CHCH2Cl

## Explanation

Chlorine of vinyl chloride (CH2==CHCl) is non-reactive substitution reaction because it shows the following resonating structure due to +M effect of –Cl atom.

In second Cl–atom has positive charge and partial double bond character with C of vinyl group, so it is more tightly attracted towards the nucleus and it does not get replaced by nucleophile in nucleophilic substitution reaction.
3

### AIPMT 2003

Which of the following pairs of compounds are enantiomers?
A
B
C
D

## Explanation

These two are non-superimposable mirror images of each other, so they are enantiomers.
4

### AIPMT 2002

Z in the above reaction sequence is
A
CH3CH2CH2NHCOCH3
B
CH3CH2CH2NH2
C
CH3CH2CH2CONHCH3
D
CH3CH2CH2CONHCOCH3