Question

A solid material is supplied with heat at a constant rate. The temperature of the material is changing with the heat input as shown in the graph. Study the graph carefully and answer the following question.
What do the horizontal regions AB and CD represent?

Answer 1

The region AB represents that the temperature of the solid material stops rising for a while in spite of the fact that heat input is being pumped. This happens when the material is a mixture of solid and liquid. Along with CD, the temperature remains constant for a longer period of time. Now the material is the mixture of a liquid and gaseous form of material.