Question

Which of the following conditions is true, when carbon dioxide diffuses out from the blood into the air inside the alveoli?

• A. The concentration of carbon dioxide is higher in blood.
• B. The concentration of carbon dioxide is higher in the air.
• C. The concentration of carbon dioxide is the same in blood and air.
• D. Nothing can be said about the concentration of carbon dioxide.

Answer 1

The correct option is A

The concentration of carbon dioxide is higher in blood.

When a substance diffuses, it moves from a region of its higher concentration to a region of its lower concentration. Carbon dioxide can be expelled from the blood into the air in the lungs only when the concentration of carbon dioxide in the blood is greater than that in the air.