AP BIOLOGY

Detailed explanation-1: -The most abundant naturally occurring gas is nitrogen (N2), which makes up about 78% of air. Oxygen (O2) is the second most abundant gas at about 21%. The inert gas argon (Ar) is the third most abundant gas at 0.93%.

Detailed explanation-2: -Earth’s atmosphere is composed of about 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, and 0.1 percent other gases.

Detailed explanation-3: -Oxygen is a major component of the solid earth, along with Si and elements such as Mg, Ca and Na. Nitrogen is not stable as a part of a crystal lattice, so it is not incorporated into the solid Earth. This is one reason why nitrogen is so enriched in the atmosphere relative to oxygen.

Detailed explanation-4: -Complete answer: Dry air in the atmosphere contains 78 % nitrogen by volume. So, nitrogen is most abundant but is unreactive.

Detailed explanation-5: -’ Nitrogen makes up 78 per cent of the air we breathe, and it’s thought that most of it was initially trapped in the chunks of primordial rubble that formed the Earth. When they smashed together, they coalesced and their nitrogen content has been seeping out along the molten cracks in the planet’s crust ever since.