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. `1//3`
C. `1//4`
D. `1//5`

Answer

B

Explanation

Equal weight of `CH_(4)` and `O_(2) = W g `
`:. nCH_(4) = W/16, nO_(2) = W/32`
Total number of moles `= W/16 + W/32 = (2W+W)/32 =(3W)/32`
Mole fraction of oxygen `n_(O_2)/(nO_(2) + n_(CH_(4)))=(W//32)/((3W//32))`
`= W/32 xx 32/(3W) = 1/3 `
Fraction of total pressure of oxygen = 1/3`