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:
Answer & explanation
Correct answer: option 2
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
$\text{(B)} < \text{(D)} < \text{(C)} < \text{(A)}$