21% of the atmosphere is oxygen.
Oxygen forms 21 percent of the Earth's atmosphere.
40 percent
Oxygen is the gas that makes up about 21 percent of the Earth's atmosphere.
The mass percent of oxygen is approximately 21% in Earth's atmosphere.
Air is 20.5 percent oxygen.
97%
The Earth
The approximate percent of oxygen in Earth's lower atmosphere is around 20.95% by volume.
Oxygen makes up about 21% of Earth's atmosphere.
Approximately 21% of Earth's atmosphere is made up of oxygen.
Oxygen composes of twenty-one percent of Earth's Atmosphere.
There is approximately 21 % oxygen in our air.