what gas makes up most of the atmosphere

Nitrogen gas makes up most of Earth’s atmosphere, at about 78% of the air by volume. Oxygen is the next most abundant, at roughly 21%, with argon and other gases making up the small remaining fraction.
Quick Scoop
- The main gas in the atmosphere is nitrogen (N2N_2N2), around 78% of dry air.
- Oxygen (O2O_2O2) is second, at about 21%, and is vital for breathing and combustion.
- Argon is a minor but significant component at just under 1%, while gases like carbon dioxide, methane, and ozone appear only in tiny trace amounts but strongly affect climate.
In simple terms: almost 4 out of every 5 “parts” of the air you breathe are nitrogen, not oxygen.
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