At what temperature does a liquid become a gas?

A liquid becomes a gas at its boiling point. This temperature is defined as the point at which the vapor pressure of the liquid equals the atmospheric pressure surrounding it, allowing the liquid to overcome intermolecular forces and transition into the gaseous phase.

In contrast, the freezing point refers to the temperature at which a liquid turns into a solid, highlighting the transition from liquid to solid. The melting point is the temperature at which a solid becomes a liquid, indicating a change in state from solid to liquid. The sublimation point involves a transition directly from solid to gas without passing through the liquid phase. Thus, the boiling point is the correct choice, as it specifically describes the temperature required for a liquid to change into a gas.