Benzene diazonium chloride when heated with warm water, would produce
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Phenol
On warming with water, the diazonium group is replaced by –OH and nitrogen gas is given off:
\( \ce{C6H5N2+Cl- + H2O} \xrightarrow{\text{warm}} \ce{C6H5OH + N2 ^ + HCl} \)
Why the other options are incorrect
Option (1) Benzene — Incorrect. Formed with a mild reducing agent such as hypophosphorous acid (\( \ce{H3PO2} \)) or ethanol.
Option (3) Chlorobenzene — Incorrect. Formed with \( \ce{Cu2Cl2} \)/HCl (Sandmeyer reaction) or copper powder/HCl (Gattermann reaction).
Option (4) Aniline — Incorrect. The amine from which the diazonium salt is made; water does not turn it back.
NCERT (2026-27 edition):
Replacement by Hydroxyl Group – “If the temperature of the diazonium salt solution is allowed to rise upto 283 K, the salt gets hydrolysed to phenol.”
\( \ce{ArN2+Cl^- + H2O -> ArOH + N2 + HCl} \)