This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: DNB 2018, Subject name: Physiology
[{'content': 'What will be the PA O2 when FiO2 is 0.5? \nSelect and explain. \nA. >100, B. >150, C. >250, D. .>500', 'role': 'user'}, {'content': 'Answer: C \nExplanation: FiO2 = fraction of O2 in inspired = 50% Pressure at sea level = 760 mm Hg According to law to paial pressures of gases, Pressures exeed by a gas in a mixture is propoional : if 50% of air is O2 PAO2 = 50 % of 760 = 380 mm Hg.', 'role': 'assistant'}]