Answer
The correct answer is:
(b) increasing the volume, keeping $P$ and $N$ constant
Work Step by Step
We can write an expression for the average kinetic energy:
$\overline{KE} = \frac{3}{2}~\frac{PV}{N}$
$\overline{KE} = \frac{3}{2}~kT$
We can see that the average kinetic energy of the gas increases if the volume increases while $P$ and $N$ remain constant.
The correct answer is:
(b) increasing the volume, keeping $P$ and $N$ constant
