Question

freezing point of a substance is same as the melting point of a solid state justify the statement with appropriate example

Answer 1

Let's consider an ice cube in your freezer.. When that ice cube is taken out of the freezer and placed in a warm kitchen, heat from the surroundings is transferred to the ice cube. We observe that the temperature of the ice cube increases. The ice cube stays a cube because the energy of the intermolecular forces that keep the water molecules together is greater than the heat energy added to the ice cube so far.

At the melting point, however, there is enough thermal energy to start breaking those intermolecular forces. What we observe is that the temperature does not rise, but bonds are breaking and the solid starts to melt. Once all the solid melts, the temperature of the (now liquid) water can increase when thermal energy is added.

A similar explanation can be used for the reverse process (freezing water) only in this case the thermal energy is being transferred from the water to the surroundings.

So we come to your question, how can melting point = freezing point. This "point" is the temperature at which the solid and liquid forms of the molecule are in equilibrium. When we use a term like melts oftentimes we mean melts completely. In this case, the temperature of the liquid would be just above the melting point.

Answer 2

So to sum this all up, when matter is transitioning from solid to liquid (melting) or liquid to solid (freezing), its temperature is fixed at the melting/freezing point, which is the same temperature