Question

please fast ...i have my exam today​

Answer 1

Yes, When body is undergoing change of state, The heat applied is used to break bonds or change the state. So, In this case, Temperature doesn't increase but heat is given continously.

Example : Melting of ice, Boiling of water.

Let's consider case of Melting of water.
Water usually melts at 0°C. Applied heat will be utilized to break the bonds between Hydrogen and Oxygen. Hence, It's true that, In some cases, Heat is constantly applied, But temperature doesn't increase.

Answer 2

It creates a change with in the object because by increase in heat energy the temperature also increase and it Changes the shape, colour etc of the object ... Example : If we heat iron it melts..
I hope it will help you