Arrange the following compounds in order of their increasing boiling points.

(A) Pentan-1-ol
(B) n-Butane
(C) Pentanal
(D) Ethoxyethane

Choose the correct answer from the options given below:

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

The correct answer is Option (2) → (B), (D), (C), (A)

Boiling point depends on intermolecular forces:

• n-Butane (B) → only London dispersion forces → lowest BP
• Ethoxyethane (D) → dipole–dipole interactions (no H-bonding)
• Pentanal (C) → stronger dipole–dipole interactions due to C=O
• Pentan-1-ol (A) → hydrogen bonding → highest BP

Increasing order of boiling points:

n-Butane < Ethoxyethane < Pentanal < Pentan-1-ol

$\text{(B)} < \text{(D)} < \text{(C)} < \text{(A)}$