Question

the alveolar PCO2 exceed or be less than 46mmhg to result in diffusion of CO2 from the blood to alveoli.

Answer 1

Dear student,
Exchange of gases in body occurs through diffusion which is the movement of particles from region of higher to lower concentration. To allow the diffusion of carbon dioxide from venous blood in lungs to alveoli, the alveoli should have lesser partial pressure of it. Partial pressure of venous blood is 46 mm Hg while that of alveolar air is 40 mm Hg.
Regards.