Which process is described as a heating process?

Which process is described as a heating process?

• A. Melting
• B. Cooling
• C. Phase-change
• D. Expanding

Answer: (A)

When heat is added to a solid, the particles gain energy. At the melting point, this extra energy goes into breaking the bonds that hold the solid together, allowing the structure to flow and become a liquid. That direct input of heat to drive a state change makes melting a heating process. Cooling removes energy and drives the reverse change. The term phase-change covers transitions between states in general but doesn’t specify heat input on its own. Expanding describes a change in size due to heating, not a change in phase, so it isn’t the process described as a heating process. Melting is the clear example of heating causing a phase change.

When heat is added to a solid, the particles gain energy. At the melting point, this extra energy goes into breaking the bonds that hold the solid together, allowing the structure to flow and become a liquid. That direct input of heat to drive a state change makes melting a heating process.

Cooling removes energy and drives the reverse change. The term phase-change covers transitions between states in general but doesn’t specify heat input on its own. Expanding describes a change in size due to heating, not a change in phase, so it isn’t the process described as a heating process. Melting is the clear example of heating causing a phase change.