A `4:1` molar mixture of `He` and `CH_(4)` 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?

Explanation

Pressure `=20 bar`
Molar ratio `=4:1` (`He` and `CH_(4)`)
`P_(He)=(4)/(5)xx20=16 bar`
`P_(CH_(4))=(1)/(5)xx20=4 bar`
`(r_(1))/(r_(2))=(P_(1))/(P_(2))xxsqrt((M_(2))/(M_(1)))`
`(r_(He))/(r_(CH_(4)))=(P_(He))/(P_(CH_(4)))xxsqrt((M_(CH_(4)))/(M_(He)))=(16)/(4)xxsqrt((16)/(4))=8`
Therefore, the ratio of moles of heilum and methane coming out initially is `8:1`.