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Isomerism · Question 30

AIPMT 2006MCQEasy📈 Topic in 0% papers+4−1
1

Which of the following is not chiral?

  1. 2-Hydroxypropanoic acid
  2. 2-Butanol
  3. 2,3-Dibromopentane
  4. 3-Bromopentane

Answer

(4) 3-Bromopentane

Solution

A molecule with a carbon atom attached to four different groups (chiral carbon) and no element of symmetry is chiral.

(1) CH3-CH(OH)-COOH: C-2 has H, OH, CH3, COOH ⇒ chiral.

(2) CH3-CH(OH)-CH2-CH3: C-2 has H, OH, CH3, C2H5 ⇒ chiral.

(3) CH3-CHBr-CHBr-CH2-CH3: C-2 and C-3 are two different chiral centres ⇒ chiral.

(4) CH3-CH2-CHBr-CH2-CH3: C-3 carries two identical ethyl groups ⇒ no chiral carbon ⇒ not chiral.

Answer: (4)

AIPMT 2006

Keep practising — Isomerism

2

The chirality of the compound [figure]

  1. R
  2. S
  3. E
  4. Z
AIPMT 2005
3

Which one of the following pairs represents stereoisomerism?

  1. Structural isomerism and geometrical isomerism
  2. Optical isomerism and geometrical isomerism
  3. Chain isomerism and rotational isomerism
  4. Linkage isomerism and geometrical isomerism.
AIPMT 2005
4

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
AIPMT 2004
5

Which of the following pairs of compounds are enantiomers?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2003
6

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
7

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
8

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
9

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

  1. meso form
  2. racemic mixture
  3. d-form
  4. l-form
AIPMT 2001
10

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
11

Dihedral angle in staggered form of ethane is

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

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