Answer: Less than 1%
Explanation:
The atmosphere is the gaseous part of the earth. in essence, it consists of only gases. The percentage distribution of gases is as follows:
Nitrogen: 78%
Oxygen: 21%
Carbon dioxide: 0.03%
unreactive gases (argon, neon etc): Remainder
Thus, since oxygen and nitrogen account for about 99%, less than 1% is the portion shared by other gases in the atmosphere
