Question

Which gas forms 21% of Earth's atmosphere?
a.-argon
b.-carbon dioxide
c.-nitrogen
d.-oxygen

Answer 1

Answer D. Oxygen

Explanation: The Earth's atmosphere is made up of approximately 78% nitrogen and 21% Oxygen.

Answer 2

Oxygen is a gas that forms 21% of the total atmosphere of Earth.

What is the significance of Oxygen?

Oxygen is a colorless and odorless gas, which is the only gas regarded as suitable for human consumption. It comprises the second-highest content of the Earths' atmospheric gases.

Hence, option D holds true that oxygen forms 21% of Earth's atmosphere.

Learn more about oxygen here:

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