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?

Question

$(a)\;4:1\qquad(b)\;6:1\qquad(c)\;8:1\qquad(d)\;2:1$