What are the primary components of air?

The primary components of air are oxygen and nitrogen, which together make up about 99% of the Earth's atmosphere. Oxygen is essential for respiration in most living organisms and is also involved in various combustion processes. Nitrogen, on the other hand, serves as a diluent for oxygen and plays a critical role in maintaining the stability and balance of the atmosphere, as it is relatively inert and does not readily react with other substances under normal conditions.

The presence of nitrogen helps to prevent rapid oxidation and contributes to the overall composition of air, making it suitable for life. While carbon dioxide is present in smaller quantities and is significant for plant photosynthesis and regulating the Earth's temperature, it is not one of the primary components of air. Similarly, hydrogen and helium are present in trace amounts and do not significantly contribute to the composition of the atmosphere. Therefore, oxygen and nitrogen are correctly identified as the primary components of air.