Which gas will diffuse at a faster rate, CH4 with a molar mass of 16 g or
SO2 with a molar mass of 64 g?

CH₄ will diffuse at faster rate.

Explanation:

According to Graham's law,

The rate of diffusion is inversely proportional to the square root of molar mas of gas.

It  is given in question the molar mass of CH₄ is 16 g. Thus the square rot of 16 is.

√16 = 4

The molar mass of SO₂ is 64 g and the square root is,

√64 = 16

As it is stated that diffusion rate is inversely related to the square root of molar mass thus the diffusion rate of  SO₂ is lower while methane diffuse faster.