The diagram below shows the change of phases of a substance on a temperature-time graph on heating the substances at a constant rate.
(a) What do the parts AB, BC, CD and DE represent?
(b) What is the melting point of the substance?
(c) What is the boiling point of the substance?
The graph shows variation of v with change in u for a mirror. Points plotted above the point P on the curve are for values of v [CPMT 1987]