Question

which of the following correctly compare the rate of diffusion of oxygen to that of hydrogen
1) 1:4
2) 4:1
3) 16:1

Answer 1

Assuming same molecular size, the diffusion coefficient scales with the random speed of thermal motion. There is also an inverse dependence upon pressure. Oxygen's thermal speed is sqrt16 = 4 times less than H2.

Because molecules are not rigid spheres, this is an approximation.