Question

for any substance why does the temperature remain constant during the change of state ​

Answer 1

Because when we provide heat to any substance to change its state then the heat is used up to overcome the force of attraction between the particles of matter. so the temperature doesn't rise.

Answer 2

The temperature of any substance remain constant during the change of state because the heat energy supplied is used up in changing the state of matter and also this heat is used for breaking of several bonds or attractive forces.This heat, which does not raise the temperature of the body, is called Laten heat.