BPSC 44th Exam Prelims 2002 Solved Paper

The atmosphere is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity. The atmosphere is composed of nitrogen (about $78\%$ ), oxygen (about $21\%$ ), argon (about $0.9\%$ ), carbon dioxide $\left(0.04\%\right)$ and other gases in trace amounts.