Question

question 1
which is the second most abundant gas in the atmosphere, at 21%?
ozone gas
nitrogen
oxygen
carbon dioxide

Explanation:

The Earth's atmosphere is composed of various gases. Nitrogen makes up about 78% of the atmosphere, oxygen about 21%, argon about 0.93%, and carbon dioxide about 0.04%. Ozone is present in very small, trace amounts in the stratosphere.

Answer:

oxygen