Question

Equal weight of $CO$ and ${CH}_4$ are mixed together in an empty container at $300K$. The fraction of total pressure exerted by ${CH}_4$ is:

• A. $\frac{16}{17}$
• B. $\frac{7}{11}$
• C. $\frac{8}{9}$
• D. $\frac{5}{16}$

Answer 1

The correct option is B $\frac{7}{11}$

Let the weight of $CO=$ weight of ${CH}_4=a$ $g$

Moles of $CO=\frac{a}{28}$

Moles of ${CH}_4=\frac{a}{16}$

Total moles $=\frac{a}{28}+\frac{a}{16}$

$x_{{CH}_4}=\frac{\frac{a}{16}}{\frac{a}{28}+\frac{a}{16}}$
$=\frac{7}{11}$

Raoult's law states that pressure exerted by the individual gas is directly proportional to its mole fraction.

$\therefore$ Fraction of pressure exerted by ${CH}_4=7/11$

Option B is correct.