<prompt> pO2 pressure at sea level:140150160180  <response>: Ans. c 160 At sea level the atmosphere exerts a total pressure of 760mmHg. Since the atmosphere is 21 02 by volume, the partial pressure of oxygen pO, 0.21 x 760 160 mmHg. The partial pressure of C02 pC02 at sea level is 0.23 mmHg. 