Question:

The compound which does not react with ammonical silver nitrate solution is:

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For Tollens’ test:

- Positive for aldehydes and formic acid.

- Ketones are generally non-reactive.

- Identify the functional group to predict reactivity.

Updated On: Jun 24, 2025

2-methyl propanal
2-methyl cyclopentanone
3-methyl benzaldehyde
Methanoic acid

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The Correct Option is B

Solution and Explanation

Ammonical silver nitrate, known as Tollens’ reagent (${[Ag(NH3)2]^+}$), is used to detect aldehydes and certain reducing compounds, which reduce ${Ag^+}$ to metallic silver, forming a silver mirror.
Step 1: Tollens’ reagent reactivity
- Aldehydes: Oxidized to carboxylic acids, reducing ${Ag^+}$.
- Ketones: Typically non-reactive due to lack of an oxidizable hydrogen.
- Methanoic acid: Reduces Tollens’ reagent due to its aldehyde-like reducing property.
Step 2: Analyze options
- (A) 2-methyl propanal (${(CH3)2CHCHO$)}: An aldehyde, reacts to form a silver mirror.
- (B) 2-methyl cyclopentanone: A ketone, does not react with Tollens’ reagent.
- (C) 3-methyl benzaldehyde (${CH3-C6H4-CHO}$): An aromatic aldehyde, reacts with Tollens’ reagent.
- (D) Methanoic acid (${HCOOH}$): Reduces Tollens’ reagent due to its reducing nature.
Step 3: Conclusion
Only 2-methyl cyclopentanone, a ketone, does not react, matching option (B).

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