Identify correct resonance structure of chlorobenzene
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → structure B
In chlorobenzene, a lone pair on chlorine is in conjugation with the π electrons of the ring. When it is shifted into the ring, a C=Cl double bond forms: chlorine, having given away electrons, carries a positive charge, and the ring carries a negative charge at the ortho or para position. This gives the C–Cl bond partial double bond character.
Structure B shows =\( \ce{Cl^{+}} \) with the negative charge at an ortho carbon, which is one of these resonance structures.
Why the other options are incorrect
Option (1) — Incorrect. The charges are reversed; chlorine donates electrons in resonance, so it cannot be negative while forming the C=Cl bond.
Option (3) — Incorrect. It carries two negative charges and no positive charge, so it is not a neutral resonance form of chlorobenzene.
Option (4) — Incorrect. Its ring is not the benzene ring with electrons shifted; resonance structures of chlorobenzene differ only in the positions of electrons.
NCERT (2026-27 edition):
Resonance Effect
