Question

For any physical state, why does the temperature remain constant during change of state

Answer 1

because the temperature is used in changing the state of matter by over coming a force of attraction between the molecules, that's why the temperature remains constant during the change of state.

Answer 2

during a physical change there takes place change in the environment i.e; increase or decrease in the temperature. If the temperature is reduced the object absorbs heat and the interparticle force is overcomed and this heat is known as latent heat