1
MCQ (Single Correct Answer)

AIPMT 2006

The general molecular formula, which represents the homologous series of alkanols is
A
CnH2nO
B
CnH2nO2
C
CnH2n + 2O
D
CnH2n + 1O

Explanation

All alcohols follow the general formula as CnH2n+2O.
2
MCQ (Single Correct Answer)

AIPMT 2005

The best method for the separation of naphthalene and benzoic acid from their mixture is
A
distillation
B
sublimation
C
chromatography
D
crystallisation.

Explanation

Sublimation would be the best method because it is applicable for those organic compounds which pass directly from solid to vapour state on heating and vice versa on cooling. In these compounds naphthalene is volatile and benzoic acid is nonvolatile due to the formation of dimer via intermolecular hydrogen bonding.
3
MCQ (Single Correct Answer)

AIPMT 2005

Which of the following undergoes nucleophilic substitution exclusively by SN1 mechanism?
A
Ethyl chloride
B
Isopropyl chloride
C
Chlorobenzene
D
Benzyl chloride

Explanation

SN1 reaction is favoured by heavy groups on the carbon atom attached to halogen i.e

Benzyl > allyl > tertiary > primary > secondary > primary > alkyl halides
4
MCQ (Single Correct Answer)

AIPMT 2005

Which amongst the following is the most stable carbocation?
A
$$\mathop C\limits^ + $$H3
B
CH3$$\mathop C\limits^ + $$H2
C
D

Explanation

3o C is more stable due to the stabilization of the charge by three methyl groups (or inductive effect). It can also be explained on the basis of hyperconjugation.

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