Oxygen and carbon dioxide pass across the alveolar membrane in the lungs through a process called

Oxygen and carbon dioxide pass across the alveolar membrane in the

lungs through a process called Diffusion.

Diffusion is defined as the movement of molecules from a region of higher

concentration to a lower concentration through a semi-permeable

membrane.

The alveolar membrane serves as the semi-permeable membrane in

which the oxygen and carbon dioxide pass through.

Read more about Diffusion here link