In humans, the amount of O₂ in the air exhaled during respiration is

In humans, the amount of O₂ in the air exhaled during respiration is [B] 16%. During respiration, oxygen is taken in from the air during inhalation and used by the body’s cells for metabolic processes. As a result, the concentration of oxygen in exhaled air is lower than inhaled air. Exhaled air typically contains approximately 16% oxygen, compared to the roughly 21% oxygen content of ambient air. The difference reflects the uptake of oxygen by the body’s tissues for cellular respiration. In addition to oxygen, exhaled air contains higher concentrations of carbon dioxide and water vapor, which are byproducts of cellular metabolism. This exchange of gases occurs in the lungs during the process of respiration, facilitating the exchange of oxygen and carbon dioxide between the bloodstream and the external environment.