Question

The state of a substance changes from one form to another on heating or cooling. Explain.

Answer 1

When a substance is heated, it gains thermal energy. Therefore, its particles move faster and its temperature rises. For example, When ice is heated it changes into water and this process is called melting.

When a substance is cooled, it loses thermal energy, which causes its particles to move more slowly and its temperature to drop. For example, when water is kept in the refrigerator its temperature falls and it turns into ice this process is known as freezing.