Question

Arrange the following compounds in increasing order of boiling points
(I) Pentan-1-ol
(II) n-Butane
(III) Pentanal
(IV) Ethoxyethane

• A. (III) < (IV) < (I) < (II)
• B. (IV) < (II) < (III) < (I)
• C. (II) < (IV) < (III) < (I)
• D. (II) < (III) < (I) < (IV)

Answer 1

Answer: (C)

Alcohols show higher b.p. because of intermoleculer $H$ -bonding. Ethers have lower b.p. than aldehyde due to weak polarity but little higher than corresponding alkane, b.p. increases with increased M.W. Thus, the overall increasing order of b.p. is
$\underset{II}{\text{n-butane}}<\underset{IV}{\mathrm{ethoxyethane}}<\underset{III}{\mathrm{pentanal}}<\underset{I}{\text{pentan-1-ol}}$