According to Graham's law, the rate of effusion of a gas is inversely proportional to square root of its molecular weight.
This can be represented as follows.
Rate of effusion ∝ 1/√M
Therefore to find which gas has highest rate of effusion, we will find out the molar masses of the given compounds. The gas that is lighter in weight would have highest rate of effusion.
1) Molar mass of oxygen (O₂) is 32 g and that of H₂ is 2.01 g . Therefore H₂ would have highest rate of effusion
2) Molar mass of methane is 16.05 [12.01 + 4 (1.01)] g and that of CCl₄ [ 12 + 4(35.45) ] is 154 g. Therefore methane will have highest rate of effusion
3) Molar mass of N₂ is 28 g and molar mass of NH₃ is [ 14 + 3(3.01) ] = 17.03 g.
Therefore NH₃ will have highest rate of effusion.
4) Molar mass of F₂ is 38 g and that of Cl₂ is 71 g. Therefore F₂ will have highest rate of effusion
