If the atmospheric pressure on mount Everest is one third the atmospheric pressure at sea level the partial pressure of oxygen on Everest is?

The partial pressure of oxygen on Mount Everest can be calculated by considering that oxygen makes up about 21% of the atmosphere. At sea level, atmospheric pressure is approximately 101.3 kPa, so one third of that is roughly 33.8 kPa on Everest. Therefore, the partial pressure of oxygen on Everest would be about 7.1 kPa (21% of 33.8 kPa).