Question

which gas in earth’s atmosphere forms ozone?
oxygen
nitrogen
water vapor
carbon dioxide

Explanation:

Ozone ($O_3$) is formed from oxygen ($O_2$) molecules in the atmosphere when they are broken apart by ultraviolet radiation and then the oxygen atoms combine with other $O_2$ molecules. Nitrogen, water vapor, and carbon dioxide do not form ozone in the same way.

Answer:

A. oxygen