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

Which test distinguishes formic acid from acetic acid?

Answer: warming with Tollens reagent.

  • A reaction with NaHCO<sub>3</sub>
  • B the ester test with ethanol
  • C warming with Tollens reagent
  • D the litmus paper test

Correct answer: C. warming with Tollens reagent

Explanation: Formic acid also has an aldehyde-like C-H and reduces Tollens reagent to give a silver mirror, whereas acetic acid does not.

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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