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Isomerism · Question 34

AIPMT 2003MCQMedium📈 Topic in 0% papers+4−1
1

Which of the following pairs of compounds are enantiomers?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]

Answer

(1) [figure]

Solution

Enantiomers are non-superimposable mirror images. In a Fischer projection the mirror image is obtained by interchanging the left and right groups on every carbon.

(1) First: –OH on C-2 right, on C-3 left (chiral, no plane of symmetry). Second: –OH on C-2 left, on C-3 right exact mirror image of the first, and not superimposable enantiomers.

(2), (3), (4): the second compound has both –OH on the same side meso form (plane of symmetry); the first is chiral the pairs are diastereomers.

Answer: (1)

AIPMT 2003

Keep practising — Isomerism

2

In this reaction : CH3CHO + HCN CH3CH(OH)CN HOH CH3CH(OH)COOH an asymmetric centre is generated. The acid obtained would be

  1. D-isomer
  2. L-isomer
  3. 50% D + 50% L-isomer
  4. 20% D + 80% L-isomer
AIPMT 2003
3

Geometrical isomers differ in

  1. position of functional group
  2. position of atoms
  3. spatial arrangement of atoms
  4. length of carbon chain
AIPMT 2002
4

A compound of molecular formula C7H16 shows optical isomerism, compound will be

  1. 2,3-dimethylpentane
  2. 2,2-dimethylbutane
  3. 2-methylhexane
  4. none of these
AIPMT 2001
5

[figure] obtained by chlorination of n-butane will be

  1. meso form
  2. racemic mixture
  3. d-form
  4. l-form
AIPMT 2001
6

2-Butene shows geometrical isomerism due to

  1. restricted rotation about double bond
  2. free rotation about double bond
  3. free rotation about single bond
  4. chiral carbon
AIPMT 2000
7

Dihedral angle in staggered form of ethane is

  1. 0
  2. 120
  3. 60
  4. 180
AIPMT 2000

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