Equal masses of methane and oxygen are mixed in an empty container at `25^(@)C`. The fraction of the total pressure exerted by oxygen is:

Options

A. `1//2`
B. `2//3`
C. `(1)/(2) xx (273)/(298)`
D. `(1)/(3)`

Answer

D

Explanation

Suppose mass of methane = mass of oxygen `= w g`
The moles of methane `= (w)/(16)`
Moles of oxygen `= (w)/(32)`
Freaction of pressure exerted by `O_(2)`
`x_(O_(2))= (n_(O_(2)))/(n_(O_(2)) + n_(CH_(4))) = (w//32)/(w//32 + w//16)`
`= (1//32)/(1//32 + 1//16) = (1//32)/(3//32) = (1)/(3)`