What does the melting point of a crystal have to do with it

What does the melting point of a crystal have to do with it

The melting point of a substance is the temperature at which the solid state and liquid state of a pure substance are in equilibrium at a certain pressure. That is to say, at this pressure and melting point, the chemical potential of a pure substance in the solid state is equal to that of a pure substance in the liquid state. However, for a pure substance solid state system (nanometer system) with great dispersion, the surface part can not be neglected.

The melting point of a substance is the temperature at which the solid state and liquid state of a pure substance are in equilibrium at a certain pressure. That is to say, at this pressure and melting point, the chemical potential of a pure substance in the solid state is equal to that of a pure substance in the liquid state. For a solid state system (nanometer system) of a pure substance with great dispersion, the surface part can not be neglected.

A sea wave is a crystal whose melting point is 48°C and whose state is:(D) Why? Is it the coexistence of solid and liquid soon to reach the melting point?

Not necessarily, like zero-degree ice and zero-degree water, but also 48.d egree. C. solid sea waves and 48.d egree. C. liquid sea waves