Air is approximately 78% N2, 21% O2 and 1% Ar by volume. At a total pressure of 1.0 bar, the partial pressure of O2 is

JEE Main levelSingle correct optionDifficulty 2 of 3ig071

Air is approximately $78%$ $N X_{2}$ , $21%$ $O X_{2}$ and $1%$ $Ar$ by volume. At a total pressure of $1.0 bar$ , the partial pressure of $O X_{2}$ is

For ideal gases volume percent equals mole percent (Avogadro), so

x_{O X_{2}} = 0.21

and

p_{O X_{2}} = 0.21 \times 1.0 = 0.21 bar