The relative humidity of ambient air at $\text{300 K}$ is $50\%$ with a partial pressure of water vapour equal to $p_{v}$. The saturation pressure of water at $\text{300 K}$ is $p_{sat}$. The correct relation for the air-water mixture is
- $p_{v}=0.5\:p_{sat}$
- $p_{v}=p_{sat}$
- $p_{v}=0.622\:p_{sat}$
- $p_{v}=2\:p_{sat}$