Which of the following gases will occupy the smallest volume at 300 K and 760 torr and why?

Question

80 g diatomic oxygen
80 g methane
80 g hydrogen fluoride

Answer 1

From PV = nRT, solve for V
V = nRT/P.
If P, R, and T are constant, then V=kn So the volume will depends only upon n. Which gas has the smallest n