What percentage of the atmosphere is composed of Nitrogen?

Nitrogen makes up approximately 78% of the Earth's atmosphere, making it the most abundant gas present. This nitrogen-rich environment plays a crucial role in supporting life on Earth. Although oxygen, which accounts for about 21% of the atmosphere, is essential for respiration in most living organisms, nitrogen is critical as it is a key component of amino acids and nucleic acids, which are necessary for biological processes and the formation of proteins and DNA.

In contrast, the other choices represent significantly smaller percentages of atmospheric composition. Oxygen, while vital, does not dominate the atmosphere in terms of volume, and carbon dioxide at 0.03% is a trace gas, albeit important for climate and plant photosynthesis. Similarly, the choice reflecting 1% is also an underrepresentation of any prevailing atmospheric gas. Consequently, understanding the predominance of nitrogen provides insight into the balance and interactions within the atmosphere that sustain various ecological and atmospheric processes.