What is the partial pressure of oxygen in the lung given the following conditions? Percentage of oxygen in air: 20 Barometric pressure: 700 mm Hg
a. 111 mm Hg
b. 124 mm Hg
c. 131 mm Hg
d. 140 mm Hg
ANS: D
The partial pressure of oxygen is equal to the percentage of oxygen in the air, 20, times the total pressure (700 mm Hg), or 140 mm Hg (700 ? 0.20 = 140).
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