The order of increasing boiling point for the following compounds is

(A) $CH_3CH_2CH_2CH_3$
(B) $CH_3CH_2CH_2 CH_2OH$
(C) $C_2H_5OC_2H_5$
(D) $CH_3CH_2CH_2CHO$

Choose the correct answer from the options given below:

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

The correct answer is Option (3) → (A), (C), (D), (B)
CH₃CH₂CH₂CH₃ < C₂H₅OC₂H₅ < CH₃CH₂CH₂CHO < CH₃CH₂CH₂CH₂OH
The order of increasing boiling point for the given compounds is
Butane < Diethyl ether < Butanal < Butanol

1. (A) CH₃CH₂CH₂CH₃ – Butane
   Non-polar molecule. Only London dispersion forces act. Hence lowest boiling point.

2. (C) C₂H₅OC₂H₅ – Diethyl ether
   Slightly polar due to C–O–C bond, so dipole–dipole forces are present, but no hydrogen bonding. Boiling point increases slightly.

3. (D) CH₃CH₂CH₂CHO – Butanal
   Contains C=O (carbonyl) group, which is strongly polar. Stronger dipole–dipole attraction than ether, so higher boiling point.

4. (B) CH₃CH₂CH₂CH₂OH – Butanol
   Has –OH group, enabling intermolecular hydrogen bonding, which is the strongest intermolecular force among these. Hence highest boiling point.