As Humidity Increases, the Partial Pressure of Oxygen in Air

Question

As humidity increases, the partial pressure of oxygen in air
A) increases as the total pressure of air remains the same.
B) increases as the total pressure of air increases.
C) decreases as the total pressure of air remains the same.
D) decreases as the total pressure of air increases.
E) does not change.

Accepted Answer

As humidity increases, the amount of water vapor in the air increases, which displaces some of the oxygen, leading to a decrease in the partial pressure of oxygen. The total pressure of the air remains the same because it is determined by the atmospheric pressure, not by the composition of the air.