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🧪 Chemistry  ·  Aldehydes, Ketones and Carboxylic Acids  ·  NEET & JEE

Which compound gives a positive Tollens' test?

Answer: Aldehyde.

  • A Ketone
  • B Aldehyde
  • C Alcohol
  • D Ether

Correct answer: B. Aldehyde

Explanation: Aldehydes reduce Tollens' reagent (ammoniacal silver nitrate) to give a silver mirror.

Nucleophilic Addition to C=ONu:-CORR'CO-RR'Nu

Curved arrows show the nucleophile attacking the carbonyl carbon while the C=O pi electrons move onto oxygen, giving a tetrahedral alkoxide intermediate.

Concept context

Aldehydes, ketones, carboxylic acids, and their derivatives (esters, amides, acid chlorides). Key reactions include nucleophilic addition, Aldol condensation, Cannizzaro, and Claisen. Very heavily tested in JEE and NEET.

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