Chemistry - Ideal Gas Question with Solution | TestHub

At the same $T$, $P$ = (m/$M$)$RT$ x (1/$V$), so the slope is proportional to the moles, m/$M$.

For equal mass, moles per gram go as 1/$M$: $He$ (4) = 0.250, $C{H}_4$ (16) = 0.0625, $Ne$ (20) = 0.050.

Steepest line 1 = $He$, line 2 = $C{H}_4$, flattest line 3 = $Ne$.

Answer: ($C$).