A Levels Chemistry (9701)•9701/13/O/N/22
Explanation
Alcohols are isomers if they share the same molecular formula but differ in structure
Steps:
- Identify molecular formulas for each alcohol based on carbon chain length and branches.
- Butan-1-ol: CH₃CH₂CH₂CH₂OH, C₄H₁₀O.
- 2-Methylpropan-1-ol: (CH₃)₂CHCH₂OH, C₄H₁₀O.
- Compare pairs: isomers require matching formulas.
- Confirm structural difference: straight chain vs. branched.
Why A is correct:
- Both have formula C₄H₁₀O, meeting isomer definition (same atoms, different arrangement).
Why the others are wrong:
- B: Pentan-1-ol is C₅H₁₂O; 2-methylpropan-1-ol is C₄H₁₀O—different carbon count.
- C: Propan-1-ol is C₃H₈O; 2-methylpropan-1-ol is C₄H₁₀O—different formulas.
- D: Propan-2-ol is C₃H₈O; 2-methylpropan-2-ol is C₄H₁₀O—mismatched atoms.
Final answer: A
Topic: Hydroxy compounds
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