Nitrobenzene is heated with $\mathrm{Sn}/\mathrm{HCl}$ and the mixture is then made alkaline. The main product is:

Metals such as $\mathrm{Sn}$ or $\mathrm{Fe}$ with $\mathrm{HCl}$ (acidic medium) reduce the nitro group completely to $-\mathrm{NH}{}_2$. The product is anilinium chloride, which liberates aniline on adding base. Azobenzene and phenylhydroxylamine arise under alkaline or neutral conditions.