21% of inhaled air is oxygen. Identify how much oxygen there is in exhaled air.

To determine how much oxygen is in exhaled air, we need to consider the usual composition of exhaled air in relation to inhaled air.

1. Inhaled Air Composition: Inhaled air consists of approximately 21% oxygen.
2. Exhaled Air Composition: During respiration, the body utilizes oxygen. On average, exhaled air contains about 16% oxygen because the body consumes some of the inhaled oxygen for metabolic processes.

Given these percentages, we can conclude that:

• The inhaled air has 21% oxygen.
• After the body uses some of this for energy, the exhaled air contains approximately 16% oxygen.

The difference in oxygen concentration reflects the oxygen consumed during respiration.

Final Answer

Exhaled air contains approximately 16% oxygen.