Approximately what percentage of the atmosphere is made up of elements other than nitrogen and oxygen?

Nitrogen and oxygen are 99% of earths atmosphere, the left 1% is other gasses.

Explanation: Earth's atmosphere is composed of about 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, and 0.1 percent other gases. Trace amounts of carbon dioxide, methane, water vapor, and neon are some of the other gases that make up the remaining 0.1 percent

d. planting trees

the trees take in carbon to make oxygen.