Which process involves gas becoming a liquid and releasing heat?

The process being described is condensation, which involves a gas transitioning into a liquid phase. During this transformation, the gas particles lose energy and come together to form a liquid. As the gas condenses, it releases heat into the surrounding environment, a phenomenon that can be understood through the principle of latent heat.

In contrast to this, evaporation refers to the process where a liquid turns into gas, absorbing heat. Melting is the transition from solid to liquid, while freezing is the change from liquid to solid, both of which do not involve a gas becoming a liquid or the release of heat in the same context. Therefore, condensation is the correct answer, as it specifically describes the process of gas turning into a liquid accompanied by the release of heat.