Multiple choice

Which gas comprises the majority of our atmosphere?

  1. Oxygen, duh because we breath it.

  2. Carbon Dioxide, duh because we exhale it.

  3. Nitrogen, duh even though humans don't use the gas.

  4. Water vapor, (duh) because of the humidity.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Earth's atmosphere is composed of approximately 78 percent nitrogen gas. Oxygen makes up about 21 percent, while carbon dioxide and other gases exist in much smaller trace amounts.

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