This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System, Subject name: Physiology
CO2 diffuses more easily through the respiratory membrane than O2 because it is- 
Select and explain. 
A. Less dense, B. More soluble in plasma, C. Less molecular weight, D. Less PCO2 in the alveoli
B: More soluble in plasma
Answer: B: More soluble in plasma 
Explanation: Ans. (b) More soluble in plasma(Ref: Ganong, 25th ed/p.639)The diffusion coefficient of CO2 is about 20 times that of O2 . So, CO2 diffuses much faster and easily than O2