Which gas is most abundant in Earth's atmosphere?

The most abundant gas in Earth's atmosphere is nitrogen, which constitutes about 78% of the atmosphere by volume. This high percentage makes it the dominant component, playing a significant role in various atmospheric processes. While nitrogen is generally considered inert and does not react easily with other substances, it serves as a vital part of the atmosphere that helps to dilute oxygen, which makes up about 21%, and other trace gases.

In contrast, oxygen is essential for life and is involved in combustion processes; however, it is not as abundant as nitrogen. Carbon dioxide, while important for climate regulation and photosynthesis, constitutes only about 0.04% of the atmosphere. Argon, a noble gas used in various applications due to its inertness, makes up about 0.93%. Therefore, nitrogen's predominance in the atmosphere is critical for maintaining the stability and balance of the Earth's environment.