Answer: Formalin.
- A Acetone
- B Formalin
- C Benzaldehyde
- D Ethanol
Correct answer: B. Formalin
Explanation: Formalin (40% formaldehyde solution) is used as a biological preservative.
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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