Question

Resonance involves
(a) migration of an H atom
(b) delocalisation of $\sigma$ electrons
(c) delocalisation of $\pi$ - electrons
(d) migration of alkyl group
The correct answer is

• A. A, B
• B. C, D
• C. C only
• D. D only

Answer 1

The correct option is C C only

Resonance only involves the delocalisation of $\pi$- electrons due to lateral overlapping of p-orbitals. $\sigma$ bonds are formed by head to head fashion hence, they are not involved in delocalisation.
Migration of $H$ and $C{H}_3$ group involve in breakage of sigma bond. Hence, they are not involved in delocalisation.
Resonance involves delocalisation of $\pi$ electron only.