$$CO_2$$ concentration is?
More in expired air than in alveolar air
More in alveolar air than in expired air
More in inspired air than in alveolar air
More in inspired air than in expired air
The correct option is B More in alveolar air than in expired air
The partial pressure of carbon dioxide in alveoli is more than the atmosphere. So the concentration of carbon dioxide is more in alveolar air than the expired air. So, the correct option is B.