What is the percentage of carbon dioxide in the air exhaled by human lungs?

4.4 percent

The correct answer is Option (4) - 4.4 percent

The percentage of carbon dioxide in the air exhaled by human lungs is approximately: 4.4 percent

When we exhale, the air leaving our lungs contains a higher concentration of carbon dioxide (CO2) compared to the air we inhale. The average concentration of carbon dioxide in exhaled air is around 4.4 percent. This concentration can vary slightly depending on factors such as metabolic rate, respiratory rate, and environmental conditions.

During respiration, cells in our body undergo metabolic processes that produce carbon dioxide as a byproduct. This carbon dioxide is transported in the bloodstream to the lungs, where it is exchanged with oxygen during the process of gas exchange in the alveoli. As a result, the air we exhale contains a higher concentration of carbon dioxide than the air we inhale.