Question

ΔH is positive for which of the following processes?

(a) Oxidation of nitrogen

(b) Melting of ice and evaporation of water

(c) Oxidation of gold

(d) Burning of chlorine

This question was posed to me in a job interview.

This intriguing question comes from Weak Interactions in Aqueous Systems topic in section Water Basics of Biochemistry

Answer 1

Correct answer is (b) Melting of ice and evaporation of water

Explanation: Enthalpy change (ΔH) is positive for endothermic reactions, the reactions which involves absorption of energy.

Melting of ice and evaporation of water involves absorption of energy.