JEE Main · 2021 · 25 Jul 2021 · Shift 2 · Compounds Containing Nitrogen

Tin and hydrochloric acid reduce the nitro group, so A is aniline. The benzenediazonium ion is a weak electrophile and can attack only a strongly activated ring; the lone pair of the amino group of aniline supplies that activation, and substitution occurs at the position para to it because the two ortho positions are crowded by the bulk of the incoming aryl group. The two rings are thus joined through an $-\mathrm{N}=\mathrm{N}-$ bridge, and the conjugation running across that bridge from the amino group accounts for the colour. P is p-aminoazobenzene.