Question

how does the mass of a molecule affect the rate of diffusion?
the lighter the molecule, the faster the rate of diffusion.
the lighter the molecule, the slower the rate of diffusion.
mass doesnt affect the rate of diffusion.
the heavier the molecule, the faster the rate of diffusion.

Explanation:

According to Graham's law of diffusion, the rate of diffusion of a gas is inversely proportional to the square - root of its molar mass. Lighter molecules (with lower mass) move faster on average and thus diffuse more quickly.

Answer:

The lighter the molecule, the faster the rate of diffusion.