What percentage of the Earth's atmosphere is made up of nitrogen?

The composition of Earth's atmosphere is primarily influenced by nitrogen, which constitutes a significant majority of its volume. Approximately 78% of the atmosphere is nitrogen. This high percentage plays a crucial role in the overall balance and health of the atmosphere, as nitrogen is a key component of the air we breathe but is not directly usable by most living organisms in its gaseous form.

The remaining portion of the atmosphere is made up of oxygen, carbon dioxide, argon, and other trace gases. Oxygen accounts for about 21% of the atmosphere, which supports life through respiration, while argon and carbon dioxide make up much smaller percentages. The other choices—1% and 5%—underrepresent the actual percentage of nitrogen, reinforcing the importance of understanding atmospheric composition in physical geography and its implications for ecological systems and climate.