Question

Equal weights of methane and helium are mixed in an empty container at ${25}^{\circ }C$, the fraction of the total pressure exerted by helium

• A. $\frac{1}{2}$
• B.
  $\frac{1}{4}$
• C. $\frac{1}{5}$
• D. $\frac{4}{5}$

Answer 1

The correct option is D $\frac{4}{5}$

Fraction of pressure exerted by helium is equal to the mole fraction of helium

moles of methane = $\frac{m}{16}$
moles of helium = $\frac{m}{4}$

mole fraction of helium = $\frac{\frac{m}{4}}{\frac{m}{4}+\frac{m}{16}}$ = $\frac{4}{5}$