Question

Equal masses of methane and oxygen are mixed in an empty container at 25 degrees centigrade. The fraction of the total pressure exerted by Oxygen is:

Options1)1/3

2)1/2

3)2/3

4)1/3*273/298

Answer is option1

Answer 1

Let the mass of methane and oxygen be m gm.

Mole fraction of oxygen, xO2 = m/32/(m/32 +m/16) = 1/3

Let the total pressure be P.

Partial pressure of O2, pO2 = P × xO2 = P x 1/3 = P/3



So option 1 is the answer