Question

why are the melting and freezing point of a substance same?

Answer 1

Melting point of any substance is the temperature at which its solid form starts to change into liquid form. On the other hand freezing point is the temperature at which liquid form starts to convert into solid form. So for any given substance the temperature at which its solid form converts into liquid form or the liquid form starts to freeze into solid form is same. It is a common temperature at below which the substance exist in solid form while above this temperature the substance exist in liquid form.