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Isomerism

AIPMT 2004MCQMedium📈 Topic in 25% papers+4−1
Ques. 1AIPMT 2004

The molecular formula of diphenylmethane, [figure] is C13H12. How many structural isomers are possible when one of the hydrogens is replaced by a chlorine atom?

  1. 6
  2. 4
  3. 8
  4. 7

Answer

(2) 4

Solution

Diphenylmethane, C6H5-CH2-C6H5, is symmetrical: both rings are equivalent.

Different kinds of H atoms:

(i) the CH2 hydrogens ⇒ C6H5-CHCl-C6H5 (1 isomer)

(ii) ring hydrogens at the ortho, meta and para positions ⇒ o-, m- and p-chloro derivatives (3 isomers)

∴ Total monochloro structural isomers = 1 + 3 = 4

Answer: (2)

Keep practising — Isomerism

Ques. 2AIPMT 2003

Which of the following pairs of compounds are enantiomers?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 3AIPMT 2003

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
Ques. 4AIPMT 2002

Geometrical isomers differ in

  1. position of functional group
  2. position of atoms
  3. spatial arrangement of atoms
  4. length of carbon chain
Ques. 5AIPMT 2001

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
Ques. 6AIPMT 2001

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

  1. meso form
  2. racemic mixture
  3. d-form
  4. l-form
Ques. 7AIPMT 2000

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
Ques. 8AIPMT 2000

Dihedral angle in staggered form of ethane is

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

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