Answer:
More heat is required for the change of state.
Step-by-step explanation:
Applied heat works at critical temperatures because at this point more heat is needed by the substance in order to change the state of substance. At critical temperatures, the substance can't melt if no more heat energy is given to the substance. A refrigerator works to cool down warm objects by absorbing heat from the inside portion of the fridge and provides cool air which cools the inner side of the fridge. The point at which a solid changes into a liquid state is called melting point while on the other hand, the point at which a liquid changes into a gaseous state is known as boiling point of a substance.