A Levels Chemistry (9701)•9701/11/M/J/20
Explanation
Identifying structural isomers via molecular formulas
Steps:
- Determine the molecular formula for each compound in the pairs.
- Compare formulas within each pair to check if they match.
- Confirm matching pairs have different connectivity for isomerism.
- Select the pair with identical formulas but distinct structures.
Why C is correct:
- Both 3-methylbutan-2-one (CH₃COCH(CH₃)CH₃) and pentanal (CH₃CH₂CH₂CH₂CHO) have the formula C₅H₁₀O, with ketone and aldehyde functional groups confirming structural isomerism.
Why the others are wrong:
- A: 2,2-Dimethylpropanoic acid is C₅H₁₀O₂; propyl methanoate is C₄H₈O₂—formulas differ.
- B: 2-Methylpropan-1-ol is C₄H₁₀O; hexan-3-ol is C₆H₁₄O—formulas differ.
- D: 3,3-Dimethylbutan-1-ol is C₆H₁₄O; pentan-3-ol is C₅H₁₂O—formulas differ.
Final answer: C
Topic: An introduction to organic chemistry
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