A Levels Chemistry (9701)•9701/12/O/N/20

Explanation
Oxidation of hydrocarbons to carboxylic acids
Steps:
- Pentanoic acid is CH3(CH2)3COOH, a 5-carbon carboxylic acid formed by oxidation cleaving C-C bonds.
- Evaluate A: Propan-1-ol (3 carbons) oxidizes to propanoic acid (3 carbons).
- Evaluate B: Butan-2-one (4 carbons) with H2SO4 undergoes acid-catalyzed reactions but not full oxidation to pentanoic acid.
- Evaluate C: Pentane (5 carbons) with hot concentrated H2SO4/KMnO4 oxidizes to pentanoic acid via cleavage.
Why C is correct:
- Oxidative cleavage of pentane (C5H12) with H2SO4(aq) (implying KMnO4 conditions) breaks the chain to yield CH3(CH2)3COOH.
Why the others are wrong:
- A: Yields propanoic acid (CH3CH2COOH), a 3-carbon acid, due to primary alcohol oxidation stopping at carboxylic acid.
- B: Ketone hydration or no reaction; does not produce a 5-carbon carboxylic acid.
- D: No reaction or information provided.
Final answer: C
Topic: Carboxylic acids and derivatives
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