Question

Equal weights of methane and oxygen are mixed in an empty container at ${25}^{\circ }C$. The fraction of total pressure exerted by oxygen is:

• A. $\frac{1}{3}$
• B. $\frac{1}{2}$
• C. $\frac{2}{3}$
• D. $\frac{1}{2}\times \frac{273}{298}$

Answer 1

The correct option is A $\frac{1}{3}$

Moles of oxygen $=\frac{x}{32}$
Moles of methane $=\frac{x}{16}$
Mole fraction of oxygen $=\frac{\frac{x}{32}}{\frac{x}{16}+\frac{x}{32}}=\frac{1}{3}$
Partial pressure $=Totalpressure\times molefraction$
$\frac{P_{O_2}}{P}=\frac{1}{3}$