What is the primary factor that affects the formation of CO₂ and H2O at the alveolar site?

Step-by-step solution

At the tissue site where partial pressure of CO2 is high due to catabolism, CO2 diffuses into blood (RBCs and plasma) and forms HCO3 and H+,. At the alveolar site where pCO2 is low, the reaction proceeds in the opposite direction leading to the formation of CO2 and H2O. Thus, CO2 trapped as bicarbonate at the tissue level and transported to the alveoli is released out as CO2 (Every 100 ml of deoxygenated blood delivers approximately 4 ml of CO2 to the alveoli.