Tollens reagent, ammoniacal silver nitrate, gives a silver mirror with
- A. ketones only
- B. both aldehydes and ketones
- C. aldehydes only
- D. neither aldehydes nor ketones
Explanation
An aldehyde still has a hydrogen on the carbonyl carbon, so it is easily oxidised to a carboxylic acid while the silver ions are reduced to metallic silver, which deposits as a mirror on clean glass. A ketone has no such hydrogen, so it resists oxidation and gives no reaction. This is the standard test for distinguishing the two classes.
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