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Q.
Equal masses of helium and oxygen are mixed in a container at $25\,{}^{\circ}C$. The fraction of the total pressure exerted by oxygen in the mixture of gases is
States of Matter
Solution:
Mole fraction of $O_{2}$ =$\frac{\frac{w}{32}}{\frac{w}{32}+\frac{w}{4}}$ = $\frac{w}{32}\times\frac{32}{9 w}$ = $\frac{1}{9}$
Partial pressure of oxygen =$P\times x_{o_2}$
=$P_{total} \times\frac{1}{9}$ or $\frac{1}{9} P_{total}$