Which gas is most abundant in the atmosphere?

Nitrogen is the most abundant gas in the atmosphere, making up about 78% of the Earth's air by volume. This colorless, odorless gas plays a crucial role in various biological processes, including the nitrogen cycle, which involves the transformation of nitrogen into different chemical forms that are essential for living organisms.

While oxygen is vital for respiration and is the second most abundant gas at around 21%, nitrogen's dominance is significant for maintaining the balance of the atmosphere. Carbon dioxide, though important for regulating the Earth's temperature and a key component of photosynthesis, constitutes only about 0.04% of the atmosphere. Hydrogen, while a light and prevalent element in the universe, is found in very small amounts in the Earth's atmosphere. This context helps clarify why nitrogen is recognized as the primary gas present in the atmosphere.