As altitude increases, which of the following atmospheric changes occurs for every 5500 m gained?
A) The proportion of oxygen decreases by 50 per cent.
B) The proportion of oxygen increases by 50 per cent.
C) The partial pressure of oxygen decreases by 50 per cent.
D) The partial pressure of oxygen increases by 50 per cent.
E) There is little change in oxygen pressure until altitudes greater than 10,000 m.

Question

Quizplus · Accepted Answer

The partial pressure of oxygen decreases by 50 per cent for every 5500 m gained in altitude. This is because the density of air (and thus the number of oxygen molecules in a given volume) decreases with altitude, leading to a decrease in the partial pressure of oxygen.

As Altitude Increases, Which of the Following Atmospheric Changes Occurs