1
MCQ (Single Correct Answer)

AIPMT 2014

Which of the following compounds will undergo racemisation when solution of KOH hydrolyses?
A
(i) and (ii)
B
(ii) and (iv)
C
(iv)
D
(i) and (iv)

Explanation

Out of the given four compounds only (iv) compound is chiral and hence only this compound will undergo racemisation.
2
MCQ (Single Correct Answer)

NEET 2013 (Karnataka)

Given :

I and II are
A
identical
B
a pair of conformers
C
a pair of geometrical isomers
D
a pair of optical isomers

Explanation

Conformers are form of stereoisomers in which isomers can be interconverted by rotation about single bonds. I and II are staggered and eclipsed conformers respectively.
3
MCQ (Single Correct Answer)

AIPMT 2012 Mains

In the replacement reaction

The reaction will be most favourable if M happens to be
A
Na
B
K
C
Rb
D
Li

Explanation

Tertiary alkyl halides shows SN1 mechanism to the greater extent. In the given reaction negative ion will attack on carbocation. Thus, greater the tendency of ionization (greater ionic character in M-F bond) more favourable will be reaction. In the given options Rb-F is most ionic and hence it will be most favourable for SN1 mechanism.
4
MCQ (Single Correct Answer)

AIPMT 2011 Mains

Consider the reactions.

The mechanisms of reactions (i) and (ii) are respectively
A
SN1   and  SN2
B
SN1   and  SN1
C
SN2   and  SN2
D
SN2   and  SN1

Explanation

These reactions are purely SN2 reactions as in reaction (i) and (ii) there is no rearrangement takes place (rearrangement occurs in SN1 mechanism). Simple substitution of nucleophile takes place.

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