Question

Which of the following is not an isomer of butanal?

• A. 2-Butanone
• B. 2-Methyl propanal
• C. 2-Butanol
• D. But-2-en-1-ol

Answer 1

Answer: (C)

2-Butanol

2-Butanol $C{H}_{3}C{H}_{2}CHOHC{H}_3$ is not an isomer of butanal $C{H}_{3}C{H}_{2}C{H}_{2}CHO$ as they have different molecular formula.
2-Butanol ha molecular formula $C_4{H}_{10}O$ and butanal has the molecular formula $C_4{H}_{8}O$.

Aldehydes and ketones are functional isomers. Hence, 2-butanone is also an isomer of butanal. 2-Methyl propanal is a chain isomer of butanal. But-2-en-1-ol is a functional isomer of butanal and both have the same molecular formula.