Question

during change of state the temperature remains constant why ?

Answer 1

Dear student,
During the change of state, the temperature remains constant. This is because all the heat supplied to the substance, converted into the vibrational or kinetic energy of the molecules. And as the vibrational energy increases the intermolecular space increases and hence intermolecular force decreases. So the heat supplied to the object is utilised in changing the state by overcoming the forces of attraction between the particles. Therefore, this heat does not contribute in increasing the temperature of the substance.
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