What is the best representation of the mass ratio of Ne:Ar in the balloons?
You are holding two balloons, an orange balloon, and a blue balloon. The orange balloon is filled with neon (Ne) gas and the blue balloon is filled with argon (Ar) gas. The orange balloon has twice the volume of the blue balloon.
PV=nRT will tell you that if everything else is constant then volume and moles have a direct relationship. If volume doubles so will moles. Twice as many moles of Neon will yield approximately the same mass as half as many moles of argon.