Question

Which of the following liquid pairs shows a positive deviation from Raoult’s law?

Options

• Water + hydrochloric acid

• Benzene + methanol

• Water + nitric acid

• Acetone + chloroform

Answer 1

Benzene + methanol

Explanation:

A positive deviation from Raoult’s law occurs when the intermolecular forces between unlike molecules (A-B) are weaker than those in the pure components (A-A or B-B). This causes more molecules to escape into vapour, resulting in higher vapour pressure and positive deviation.