Carboxylic acids' characteristic reactions

Steps:

• Recall that carboxylic acids have the functional group -COOH and undergo specific reactions like esterification.
• Evaluate each option against known properties: oxidation, unsaturation tests, ester formation, and reaction with bases.
• Identify that esterification with alcohols is a defining reaction for carboxylic acids.
• Confirm no other option accurately describes a standard carboxylic acid property.

Why C is correct:

• Carboxylic acids react with alcohols in the presence of an acid catalyst to form esters via the esterification reaction: RCOOH + R'OH → RCOOR' + H₂O.

Why the others are wrong:

• A: Carboxylic acids are prepared by oxidation of primary alcohols or aldehydes, not alkanes.
• B: They do not decolourise bromine water, as they lack carbon-carbon double bonds; alkenes do.
• D: They react with carbonates to form a salt, carbon dioxide, and water, not hydrogen.

Final answer: C