Which of the following gases is not considered a major atmospheric gas?

Ozone is not considered a major atmospheric gas because it exists in relatively small concentrations compared to other gases such as nitrogen, oxygen, and argon, which make up the bulk of the Earth's atmosphere. The major atmospheric gases are those that comprise over 99% of the atmosphere, primarily nitrogen (about 78%), oxygen (about 21%), and argon (around 0.93%). These gases are crucial for supporting life and maintaining the planet's climate.

Ozone, on the other hand, while significant for its role in absorbing harmful ultraviolet radiation in the stratosphere, is present in much smaller quantities; it is not a major component of the tropospheric atmosphere where most weather phenomena occur. Thus, understanding the distinction between major atmospheric gases and trace gases like ozone is essential in environmental science and atmospheric studies.