Question

Choose the correct statement(s) :

• A. Phenyl group can show $-R$ effect
• B. In chlorobenzene , $-Cl$ shows $+I$ effect
• C. Phenyl group can show $+R$ effect
• D. $-CH=C{H}_2$ can show both $+R$ and $-R$ effect.

Answer 1

Answer: (A), (C), (D)

The correct options are
A Phenyl group can show $-R$ effect
C Phenyl group can show $+R$ effect
D $-CH=C{H}_2$ can show both $+R$ and $-R$ effect.

In chlorobenzene, due to higher electronegativity of chlorine as compared to carbon, it acts as an electron withdrawing group, and hence shows $-I$ effect.
Flexible groups :
Atoms/ group attached to the conjugated system which show both +M/−M effect.
Examples :$-N=O,-SH,-Cl,-P{H}_2,-N=N,-Phenyl,-CH=C{H}_2$ etc.