Question

The densities of 4 gases at standard temperature and pressure are given in the table

Gas	Methane	Ammonia	Helium	Neon
Density	0.72 g/L	0.77 g/L	0.18 g/L	0.90 g/L

Among these gases, which gas diffuses very fast? State the law that helps you to take the decision.

Answer 1

According to Graham's law of diffusion, the rates of diffusion, under similar conditions of temperature and pressure, the rates of diffusion of gases are inversely proportional to the square root of their densities.
Helium, with lowest density (0.18 g/L) will have maximum rate of diffusion and will diffuse very fast.