Identify the product of the following reaction.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → aniline
Nitro compounds are reduced to amines by catalytic hydrogenation: hydrogen gas is passed in the presence of finely divided nickel, palladium or platinum. Each nitro group takes up three molecules of hydrogen, and its two oxygen atoms leave as water. The benzene ring is not touched under these conditions.
\( \displaystyle \ce{C6H5NO2 + 3H2} \xrightarrow[\text{ethanol}]{\ce{Pd}} \ce{C6H5NH2 + 2H2O} \)
So nitrobenzene gives aniline.
Why the other options are incorrect
Option (1) 4-nitrobenzaldehyde — Incorrect. It still has the nitro group and has gained a –CHO carbon; hydrogenation adds hydrogen, not carbon.
Option (2) 4-nitrobenzoic acid — Incorrect. Adding a –COOH group is an oxidation and needs a carbon source; neither happens with \( \ce{H2/Pd} \).
Option (4) toluene — Incorrect. The nitro group is reduced to –\( \ce{NH2} \), not replaced by a methyl group.
NCERT (2026-27 edition):
Reduction of Nitro Compounds
