\([Ag(NH_3)_2]OH\) forms silver when it reacts with
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → HCOOH
\( \ce{[Ag(NH3)2]OH} \) is Tollens’ reagent. It is reduced to metallic silver (silver mirror) by compounds that are easily oxidised, such as aldehydes. Formic acid (HCOOH) contains an aldehyde-like H–C=O group, so it reduces Tollens’ reagent and is itself oxidised to \( \ce{CO2} \) and water:
\( \ce{HCOOH + 2[Ag(NH3)2]+ + 2OH- -> 2Ag v + CO2 + 2H2O + 4NH3} \)
Why the other options are incorrect
Option (1) CH3CH2OH — Incorrect. Ethanol is a primary alcohol; Tollens’ reagent is too mild an oxidant to oxidise alcohols.
Option (2) CH3OCH3 — Incorrect. Dimethyl ether has no oxidisable group and does not react.
Option (4) CH3COCH3 — Incorrect. Acetone is a ketone; ketones are not oxidised by mild oxidising agents and give no silver mirror.
NCERT (2026-27 edition):
Oxidation – …
