The atmospheric pressure is 1.0 atm and Henry’s law constant for O2 is 1.66 x 10-6 M/mm Hg at 25 °C. Assume air contains 21% oxygen. Calculate the partial pressure of oxygen. (21% of air is oxygen and the mole fraction of O2 is 0.21).$

• A. 180 mm Hg
• B. 130 mm Hg
• C. 120 mm Hg
• D. 160 mm Hg