Question

A liquid is in equilibrium with its vapor at its boiling point. On the average, the molecules in the two phases have equal:

• A. inter-molecular forces
• B. potential energy
• C. kinetic energy
• D. total energy

Answer 1

The correct option is C kinetic energy

According to kinetic theory, average kinetic energy $\left(ϵ\right)=\frac{3}{2}{k}_{B}T$.
Where, $k_B$ is Boltzmann's constant. Thus kinetic energy is directly proportional to temperature.
When the liquid is in equilibrium with its vapour pressure at its boiling point, the molecules in two phases have same kinetic energy as they are at same temperature.