Question

Equal amounts of two gases of molecular mass 4 and 40 are mixed. the pressure of the mixture is 1.1 atm. The partial pressure of the light gas in this mixture is :

• A. 0.55 atm
• B. 0.11 atm,
• C. 1 atm
• D. o.12 atm

Answer 1

The correct option is C 1 atm

Assume 40 g each of two gases is present.

The number of moles of lighter gas are $\frac{40}{4}=10$.

The number of moles of heavier gas are $\frac{40}{40}=1$.

The mole fraction of the lighter gas is $\frac{10}{10+1}=0.9090$.

The partial pressure of the lighter gas is $0.9090\times 1.1=1atm$.