1

NEET 2016 Phase 2

Which of the following can be used as the halide component for Friedel-Crafts reaction?
A
Chlorobenzene
B
Bromobenzene
C
Chloroethane
D
Isopropyl chloride

Explanation

Friedel–Crafts reaction :

Chlorobenzene, bromobenzene and chloroethene are not suitable halide components as lone pair of electrons of halogen are delocalized with $\pi$-bonds to attain double bond (C = X) character.
2

NEET 2016 Phase 2

In which of the following molecules, all atoms are coplanar?
A
B
C
D

Explanation

Biphenyl is coplanar as all carbon atoms are sp2 hybridised.
3

AIPMT 2015 Cancelled Paper

Given :

The enthalpy of hydrogenation of these compounds will be in the order as
A
II > III > I
B
II > I > III
C
I > II > III
D
III > II > I

Explanation

Enthalpy of hydrogenation is inversely proportional to the stability of alkenes.

Stability of alkenes : I $>$ II $>$ III

Enthalpy of hydrogenation : I $<$ II $<$ II
4

AIPMT 2015 Cancelled Paper

A single compound of the structure,

is obtainable from ozonolysis of which of the following cyclic compounds?
A
B
C
D