What process occurs when a solid becomes a liquid?

The process that occurs when a solid becomes a liquid is known as melting. During melting, a solid absorbs heat energy, causing the molecules within it to gain kinetic energy and move more freely. As the temperature increases, the structured arrangement of molecules in the solid breaks down, transitioning it into a liquid state.

Understanding this phase change is essential because it is a fundamental concept in thermodynamics and material science. The other processes mentioned involve different changes in state: condensation is the change from gas to liquid, freezing is the transition from liquid to solid, and evaporation is the change from liquid to gas. Thus, the correct term for the solid-to-liquid transition is melting.