In our daily life we generally find mixture of gases e.g. air contains N2, O2, H2, etc.

To find the composition of mixture of two gases, we should know the mass of the gas and effective molecular weight of the gas, where effective molecular weight is defined as

(Mo)effective =

Where n1, n2, n3 are the no. of mole of gas 1, 2, 3, etc. and (Mo)1, (Mo)2, (Mo)3 are the molecular weight of gas 1,2 , 3 etc.

We take a sample of gas off course more than one mole of the gas and then by some special instrument we measure the mass of the gas, which is indicated by M. Then we place some gas in a container of volume 22.4 λ and we maintain the pressure at 1 atm and temperature 0°C, so that container contain exactly one mole of gas and then by same special instrument we measure the mass of gas which is molecular weight of mixture and is indicated by M 0 . The division of quantity gives no. of mole of the gas in the sample.

(i) If for air (N 2 + O 2 ) the mass is 50 gm and the molecular weight is 30 gm. Then the no. of mole of N 2 in the sample is