Atmospheric Pressure at Sea Level Is 760 Mm Hg, and Oxygen

Multiple Choice

Atmospheric pressure at sea level is 760 mm Hg, and oxygen makes up 20.9% of this air when the air is dry.Scientists at a Mount Everest base camp measured the atmospheric pressure there as 400 mm Hg.When the air is dry, the partial pressure of oxygen at this base camp is approximately _______ mm Hg.

A) 21
B) 40
C) 84
D) 160
E) 400