Calculate the ratio of effusion rates between helium and radon gases

From Graham's law of diffusion the effusion rate of a gas is inversely proportional to the square root of its molar mass.

Therefore for helium and radon; Helium has a mass of 4 g while randon has 222, hence;

= √222/√4

= 14.90/2

= 7.45

Thus the ratio of effusion rate between helium and randon is 7.45