AP BIOLOGY

Detailed explanation-1: -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.

Detailed explanation-2: -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-3: -Gases. The most abundant naturally occurring gas is nitrogen (N2), which makes up about 78% of air.

Detailed explanation-4: -The other primary reason is that, unlike oxygen, nitrogen is very stable in the atmosphere and is not involved to a great extent in chemical reactions that occur there. Thus, over geological time, it has built up in the atmosphere to a much greater extent than oxygen.

Detailed explanation-5: -In fact, nitrogen is the most abundant element in Earth’s atmosphere: approximately 78% of the atmosphere is nitrogen! Nitrogen is important to all living things, including us.