What is the most abundant gas in the Earth's atmosphere?

Nitrogen is the most abundant gas in the Earth's atmosphere, making up about 78% of the atmosphere's composition. This high concentration plays a vital role in supporting life and influencing various atmospheric processes.

Oxygen, while essential for many living organisms, constitutes approximately 21% of the atmosphere. Carbon dioxide is present in much smaller amounts, around 0.04%, but it is crucial for photosynthesis and regulating the Earth's temperature. Hydrogen is the least abundant of these gases, occurring in trace amounts. Understanding the composition of the atmosphere helps explain climate dynamics and ecological interactions on Earth.