Air is composed of what percent of oxygen?

The correct answer is that air is composed of 21% oxygen. This is a fundamental concept in atmospheric science and is critical for understanding the composition of Earth's atmosphere.

Oxygen plays a vital role in processes such as respiration for animals and combustion. While the exact percentage of oxygen can vary slightly depending on factors like altitude and pollution, the standard composition at sea level is approximately 21%.

Nitrogen makes up the majority of the atmosphere, at about 78%, while the remaining percentage consists of other gases like argon, carbon dioxide, and trace gases. Understanding these proportions is essential for various applications, including agriculture, where oxygen levels can affect plant growth and soil health.