What gas is most prevalent in Earth's atmosphere?

The gas that is most prevalent in Earth's atmosphere is nitrogen. It constitutes about 78% of the total atmosphere. This large proportion plays a crucial role in various environmental and biological processes. Nitrogen is relatively inert and does not easily react with other substances, which helps stabilize the atmosphere and maintain its composition.

In contrast, oxygen, while essential for most life forms and comprising around 21% of the atmosphere, does not dominate its overall makeup. Carbon dioxide and argon make up only a small fraction of the atmosphere, with carbon dioxide accounting for about 0.04% and argon approximately 0.93%. Thus, understanding the composition of the atmosphere highlights the significance of nitrogen not only in terms of its abundance but also its function in supporting life through the nitrogen cycle and maintaining ecological balance.