What occurs at the melting point?

The melting point is defined as the temperature at which a solid turns into a liquid. During this process, the solid absorbs heat energy, which causes the particles in the solid to gain enough kinetic energy to overcome the forces holding them in a rigid structure. As a result, the material transitions from a solid to a liquid state while maintaining its chemical composition and structure.

This means that the change at the melting point is a physical change, not a chemical one, thus the material itself does not undergo any structural transformation other than the change from a solid to a liquid. The other choices highlight different processes or phases: the first refers to vaporization, the third implies a chemical reaction which does not happen at the melting point, and the fourth relates to the absorption of heat without a phase change, which is not the case as melting involves a distinct change in state.