Which gas makes the greatest percentage of Earths atmosphere? And what is its characteristics?

Nitrogen and Oxygen

Explanation:

Nitrogen and oxygen are by far the most common; dry air is composed of about 78% nitrogen (N2) and about 21% oxygen (O2). Argon, carbon dioxide (CO2), and many other gases are also present in much lower amounts; each makes up less than 1% of the atmosphere's mixture of gases.

the words "strangest" and "unusual" suggest (:

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