How many more resonating structures does aniline have than anilinium ion?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 3
In aniline the lone pair on nitrogen is in conjugation with the benzene ring, so it can be delocalised into the ring. In the anilinium ion, \( \ce{C6H5NH3^+} \), this lone pair is used in the bond to \( \ce{H^+} \), so nitrogen has no lone pair left to delocalise.
Aniline: the two Kekulé structures of the ring (2), plus three structures in which the lone pair has moved into the ring, putting a negative charge at one ortho position, the para position and the other ortho position, with \( \ce{=NH2^+} \) on the ring (3). Total 5 structures.
Anilinium ion: only the two Kekulé structures of the ring. Total 2 structures.
Difference: 5 − 2 = 3 more structures for aniline.
NCERT (2026-27 edition):
9.6 Chemical Reactions
