Question

The following figure represents the temperature versus time plot for a given amount of a substance when heat energy is supplied to it at a fixed rate and at a constant pressure. Which part of the plot represents phase change?

• A. $a$ to $b$ and $e$ to $f$
• B. $b$ to $c$ and $c$ to $d$
• C. $d$ to $e$ and $e$ to $f$
• D. $b$ to $c$ and $d$ to $e$

Answer 1

The correct option is D $b$ to $c$ and $d$ to $e$

For interval $b$ to $c$ and $d$ to $e$, temperature is not changing with time even when heat energy is supplied to it at a fixed rate.
$\therefore$ During this time interval, phase change occurs..