Question

Breathe in, breathe out, most of the gas that just passed through your mouth is:

Oxygen, Nitrogen, Water Vapor, or CO2?

Answer 1

The answer is: [B]: "Nitrogen" (N₂ gas); which is the most prevalent gas in the Earth's atmosphere.
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Answer 2

The environment we are in is 1.5% filled with CO2 exhaled from our own body and others.But there is more nitrogen than any other gases on earth.So the answer is Nitrogen .