What is the volume percentage of oxygen in the air?

The volume percentage of oxygen in the air is approximately 20.91%. This is based on the composition of Earth's atmosphere, which consists of about 78% nitrogen, 21% oxygen, and trace amounts of other gases such as argon, carbon dioxide, and neon.

When considering the major components of air, nitrogen is the predominant gas, making up the largest percentage, while oxygen is the second most abundant. The presence of oxygen at approximately 20.91% is crucial for various biological and chemical processes, including respiration in living organisms and combustion in engines.

Understanding the composition of air is essential for engineers and those working in fields related to environmental health, combustion systems, and atmospheric sciences. Recognizing the accurate volume percentage also helps in calculating factors like stoichiometric ratios for combustion reactions, ventilation requirements, and assessing air quality in different environments.