A Levels Chemistry (9701)•9701/11/O/N/20

Explanation
Enumerating C3H6ClO alcohol isomers with structural and stereo variants Steps:
- Consider acyclic structures based on allyl alcohol (CH2=CHCH2OH) with Cl substitution: Cl on terminal vinyl gives E/Z isomers (2); Cl on internal vinyl gives 1 achiral isomer; Cl on CH2OH gives chiral center (2 enantiomers).
- Consider cyclic structures from cyclopropanol: geminal Cl/OH on same carbon (1 isomer); adjacent Cl/OH gives cis/trans stereoisomers (2).
- Total: 5 acyclic + 3 cyclic = 8 alcohol isomers.
- Subtract 3 given (X, Y, Z) yields 5 other isomers.
Why D is correct:
- Molecular formula C3H6ClO allows 8 alcohol isomers (5 acyclic + 3 cyclic) per structural and stereochemical analysis, minus 3 shown equals 5.
Why the others are wrong:
- A: Ignores stereoisomers like E/Z or enantiomers.
- B: Misses cyclic variants or full stereo count.
- C: Overlooks one stereoisomer pair or structure.
Final answer: D
Topic: Hydroxy compounds
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