Answer: Aliphatic aldehydes.
- A Ketones
- B Aliphatic aldehydes
- C Aromatic aldehydes
- D Ethers
Correct answer: B. Aliphatic aldehydes
Explanation: Aliphatic aldehydes reduce Fehling's solution to give Cu<sub>2</sub>O (brick-red precipitate).
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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