When we decrease the temperature, less heat energy is supplied to the atoms, and so their average kinetic energy decreases. When they enter a phase transition, such as freezing from a liquid to a solid, the temperature is not decreasing or increasing, and stays constant
when the kinetic energy of a particle decreases, according to me that body must have been freeze, like water particles or intermolecular force which losses when heated (gains more kinetic energy) and when freeze losses kinetic energy.
