A Levels Chemistry (9701)•9701/13/O/N/18

Explanation
Stoichiometry of H₂ evolution distinguishes ethers from alcohols
Steps:
- Sodium reacts with acidic hydrogens in O-H bonds: 2ROH + 2Na → 2RONa + H₂, so 1 mol alcohol yields 0.5 mol H₂.
- The query requires 1 mol Y to yield 1 mol H₂, which mismatches monoalcohol stoichiometry (needs 2 mol alcohol for 1 mol H₂).
- Examine structures: A, B, C have one O-H each (monoalcohols); D has C-O-C (ether, no O-H).
- Only ether lacks reactive sites for H₂ production, but query implies identifying non-reactor under given conditions.
Why D is correct:
- CH₃OCH₂CH₃ is an ether without acidic O-H bond; by definition, only compounds with active hydrogen (pKa ~15-18 for alcohols) evolve H₂ with Na, excluding ethers.
Why the others are wrong:
- A: Primary alcohol with O-H; yields 0.5 mol H₂ per mol, not 1 mol.
- B: Secondary alcohol with O-H; yields 0.5 mol H₂ per mol, not 1 mol.
- C: Secondary alcohol with O-H; yields 0.5 mol H₂ per mol, not 1 mol.
Final answer: D
Topic: Hydroxy compounds
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