Refer to the plot of temperature versus time (Fig. 11.2) showing the changes in the state of ice on heating (not to scale).

Which of the following is correct?

As we know whenever any substance get heated continuously but its temperature not changing, then obviously the state changes i.e. solid to liquid or liquid to gas or similarly.

Now look carefully the above graph, we are seeing that part AB (0℃) and CD (100℃) represents the conversion of solid into liquid and liquid into gas respectively. That means part AB represents ice and water both till B, and part CD represents water and steam.

So from above we can say that option (b) is wrong and also option (c) is wrong because at D all waters get converted into steam. Hence options (a) & (d) are correct.