1

### AIPMT 2008

How many stereoisomers does this molecule have?

CH3CH$=$CHCH2CHBrCH3
A
8
B
2
C
4
D
6

## Explanation

Both geometrical isomerism (cis-trans form) and optical isomerism is possible in the given compound.

No. of optical isomer = 2n = 21 = 2
(where n = no. of asymmetric carbon)

Hence total no. of stereoisomers = 2 + 2 = 4
2

### AIPMT 2007

If there is no rotation of plane polarised light by a compound in a specific solvent, through to be chiral, it may mean than
A
the compound is certainly meso
B
there is no compound in the solvent
C
the compound may be a racemic mixture
D
the compound is certainly a chiral.

## Explanation

Compounds which do not show optical activity inspite of the presence of chiral carbon atoms are called meso-compounds. The absence of optical activity in these compound is due to the presence of a plane of symmetry in their molecules. e.g. meso-tartaric acid is optically inactive.
3

### AIPMT 2007

CH3 $-$ CHCl $-$ CH2 $-$ CH3 has a chiral centre. Which one of the following represents its R-configuration?
A
B
C
D

## Explanation

4

### 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.