The reduction of the nitro group ($-N{O}_2$) to the amino group ($-N{H}_2$) can be achieved through several methods:

• In Acidic Medium: Nitrobenzene is reduced using metals like Tin ($Sn$) or Iron ($Fe$) with concentrated $HCl$. Reaction: $C_6{H}_{5}N{O}_2+6[H]\stackrel{Sn/HCl}{\to }{C}_6{H}_{5}N{H}_2+2H_{2}O$
• The product is Aniline.
• Iron scrap and $HCl$ is preferred industrially because the generated $FeC{l}_2$ is hydrolyzed to release $HCl$, thus only a small amount of acid is initiated for the whole process.