Arrange the following compounds in increasing order of boiling point.

(A) Ethanol
(B) Diethyl ether
(C) Ethanal
(D) Ethane

Choose the correct answer from the options given below:

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

The correct answer is Option (4) → (D), (B), (C), (A)

First, compare the intermolecular forces and typical boiling points:

• Ethane (D) → non-polar, only weak London forces → lowest b.p.
• Diethyl ether (B) → weak dipole–dipole, no H-bonding
• Ethanal (C) → stronger dipole–dipole interactions (carbonyl group)
• Ethanol (A) → hydrogen bonding → highest b.p.

So, the increasing order of boiling point is:

Ethane < Diethyl ether < Ethanal < Ethanol