Arrange the following compounds in the decreasing order of their boiling points:

(A) Butyraldehyde
(B) n-Butyl alcohol
(C) Sec-butyl alcohol
(D) n-butane

Choose the correct answer from the options given below:

(B), (C), (A), (D)

The correct answer is Option (3) → (B), (C), (A), (D)

To arrange them in decreasing order of boiling points, consider the intermolecular forces:

• Alcohols have hydrogen bonding → highest boiling points
• Among alcohols, less branched (n-butyl alcohol) has a higher boiling point than more branched (sec-butyl alcohol)
• Aldehydes have dipole–dipole interactions (no H-bonding)
• Alkanes have only weak London forces → lowest boiling point

So the order is:

n-Butyl alcohol (B) > sec-Butyl alcohol (C) > Butyraldehyde (A) > n-Butane (D)