please watch this video then answer the question below :
Robert Hines celebrated his graduation from college by going to Alaska for some climbing. Robert is in excellent physical condition: he runs 5 miles daily, played intramural spikeball, and was a volunteer firefighter. Because his parents are obligated to pay his private student loans after his death, they had Robert undergo a complete medical examination before climbing Mount Vancouver. The summit is approximately 15,787 feet above sea level, and the barometric pressure is around 420 mm Hg (sea level is 760 mm Hg).
1.At his physical examination (performed at sea level), Roberts’s arterial Po2 (PaO2) was 100 mm Hg. If Robert’s PaO2 had been measured when he arrived on Mount Vancouver, it would have been approximately 50 mm Hg. Why would his PaO2 be decreased at the higher elevation? You need to explain the fractional concentration of O2 (FIO2) in atmospheric air in your answer.
2.Predict whether each of the following parameters would be increased, decreased, or unchanged on Mount Vancouver. Explain why each of the predicted changes would occur.
b.Percent saturation of hemoglobin
c.Po2 at which hemoglobin is 50% saturated (P50)
d.Pulmonary artery pressure
3.Regarding Robert’s arterial Pco2 (PaCO2) on Mount Vancouver:
a.Would it increase, decrease, or not change compared with normal? Why?
b.If you predicted a change in PaCO2, what effect would this change have had on arterial pH?
c.What acid–base disorder would it have caused?
Explain why a physician might prescribe acetazolamide as a prophylactic. How does this help with the acid-base disorder