Q.Which one of the following reduces Tollens' reagent? a) formic acid b) acetic acid c) benzophenone d) none of these

Step 1. Reducing Tollens' reagent (silver mirror test) requires a compound that is itself readily oxidisable -- classically, an aldehyde's own C-H (Section 12.6).

Step 2. Formic acid, HCOOH, is structurally unique among carboxylic acids: its single carbon carries BOTH the acid's -OH/=O AND a genuine aldehyde-type C-H, so it behaves like a true aldehyde and DOES reduce Tollens' reagent (Section 12.12.E). …

Check each option for an aldehyde-type C-H directly on a carbonyl/carboxyl carbon -- only formic acid has one, since it is the one-carbon acid where th …

• Assuming any carboxylic acid can reduce Tollens' reagent simply because it is 'oxidisable' in a general sense -- the specific structural requirement is an aldehyde-ty …