At the summit of a high mountain, the atmospheric pressure is 380 mm Hg. If the atmosphere is still composed of 21% oxygen, then the partial pressure of oxygen at this altitude is
A) 0 mm Hg.
B) 80 mm Hg.
C) 160 mm Hg.
D) 380 mm Hg.
E) 760 mm Hg.

Question

Quizplus · Accepted Answer

The partial pressure of oxygen at a certain altitude can be found by multiplying the atmospheric pressure at that altitude with the fraction of oxygen in the atmosphere. In this problem, the atmospheric pressure is given as 380 mm Hg, and the fraction of oxygen is given as 21%. Therefore, the partial pressure of oxygen at this altitude is:

Partial pressure of oxygen = Atmospheric pressure x Fraction of oxygen
Partial pressure of oxygen = 380 mm Hg x 0.21
Partial pressure of oxygen = 79.8 mm Hg (rounded off to 80 mm Hg)

Therefore, the best choice is B) 80 mm Hg.

At the Summit of a High Mountain, the Atmospheric Pressure