As hot gases cool, they release heat energy primarily by changing from which state to another?

The correct answer is the transition from a gas to a liquid. When hot gases cool, they undergo a process known as condensation. During condensation, the gas loses heat energy and transitions into a liquid state. This is a fundamental principle of thermodynamics and is commonly observed in everyday situations, such as when steam from boiling water condenses into water droplets on a cooler surface.

The cooling process involves the gas molecules losing kinetic energy, which allows them to come closer together and form intermolecular bonds, resulting in a liquid. This phase change is accompanied by the release of latent heat, which is the heat energy released during the transition from gas to liquid.

Other options represent different phase changes that do not primarily occur when hot gases cool. For instance, transitioning from a liquid to a solid typically involves freezing rather than cooling of gases, and moving from a solid to a gas is indicative of sublimation, which requires heat absorption rather than release. Likewise, a vapor to a gas is not a valid transition for cooling, as vapor and gas are often used interchangeably in various contexts and do not represent a cooling process. Thus, the cooling of hot gases primarily involves their transition to a liquid state.