SOLAR SYSTEM

Detailed explanation-1: -The air in Earth’s atmosphere is made up of approximately 78 percent nitrogen and 21 percent oxygen. Air also has small amounts of other gases, too, such as carbon dioxide, neon, and hydrogen.

Detailed explanation-2: -Oxygen is the next most abundant gas, present at levels of 20 to 21%. Although humid air seems like it contains a lot of water, the maximum amount of water vapor that air can hold is only about 4%.

Detailed explanation-3: -In fact, the troposphere contains three-quarters of the mass of the entire atmosphere. The air here is 78% nitrogen and 21% oxygen. The last 1% is made of argon, water vapor, and carbon dioxide.

Detailed explanation-4: -The Earth’s atmosphere is about 21 percent oxygen. But it hasn’t always been. There have been ups and downs in oxygen levels and they may have played a role in mass extinctions and the evolution of mammals.