A 4: 1 molar mixture of He and CH4 is contained in a vessel at 20 bar pressure. Due to a hole in the vessel, the gas mixture leaks out. What is the composition of the mixture effusing out initially?

Answer

`(8 : 1)`

Explanation

`(r_(He))/(r_(CH_(4))) = (n_(He))/(n_(CH_(4))) sqrt((M_(CH_(4)))/(M_(He))) = (4)/(1) sqrt((16)/(4)) = 8`
Initial ratio of rates of effusion gives the initial composition of mixture effusing out.
Therefore `n(He) : n(CH_(4)) = 8 : 1`