graham's law of diffusion

Firstly let me tell something about diffusion. DIffusion is the intermxing of two or more gases. Effusion is a special case of diffusion wherein the intermixing of gases takes palce through a small opening under pressure. Effusion is followed by the process of diffusion. So, when this intermixing of gases takes place, the rate of diffusion or effusion for different gases is different. Sone diffuse at a faster rate and some diffuse at a slower rate.

According to Graham's law of diffusion, under identical conditions of temperature and pressure, the rate of siffusion or effusionof a gas is inversely proportional to the square root of its density.

So, if we know the molecular masses we can know that rate of diffusion or effusion of a gas.