Correct Option
The correct option is (c) 1 and 3 only.
Explanation
Breathing involves the inhalation of atmospheric air and the exhalation of alveolar air. While the process involves the exchange of gases (uptake of oxygen and release of carbon dioxide), the physical state of the air remains a gaseous mixture throughout.
Statement-wise Analysis
- Statement 1 is Correct: The air inhaled is a mixture of gases found in the atmosphere. It consists primarily of Nitrogen (approximately 78%), Oxygen (approximately 21%), Argon, Carbon Dioxide (0.03–0.04%), and water vapor. Nitrogen enters the lungs but is not utilized in the metabolic process.
- Statement 2 is Incorrect: Exhaled air is not completely devoid of oxygen. The human body utilizes only a fraction of the oxygen inhaled. Exhaled air typically contains about 16% Oxygen (reduced from 21%) and approximately 4% Carbon Dioxide (increased from 0.04%).
- Statement 3 is Correct: Both inhaled and exhaled air retain the properties of a mixture. They contain Nitrogen, Oxygen, Carbon Dioxide, and other trace gases, differing only in their relative proportions and water vapor content.
Key Takeaway: Respiration does not consume all oxygen from the air. Exhaled air still contains a significant percentage of oxygen (~16%), which is the scientific basis for the effectiveness of rescue breathing (CPR).