Which set of gases are the four most abundant in dry air?

Which set of gases are the four most abundant in dry air?

• A. Nitrogen, Oxygen, Argon, Carbon Dioxide
• B. Nitrogen, Oxygen, Neon, Carbon Dioxide
• C. Nitrogen, Helium, Oxygen, Argon
• D. Oxygen, Nitrogen, Carbon Dioxide, Argon

Answer: (A)

The main idea is the typical composition of dry air by volume. The two largest components are nitrogen and oxygen, making up about 78% and 21% of air respectively. After these, the next most abundant gases are argon, around 0.9%, and carbon dioxide, about 0.04%. Other gases like neon or helium exist in much smaller amounts, so they don’t rank in the top four. Therefore, the four most abundant gases in dry air are nitrogen, oxygen, argon, and carbon dioxide. The exact order doesn’t matter, so any listing that includes those four is correct.

The main idea is the typical composition of dry air by volume. The two largest components are nitrogen and oxygen, making up about 78% and 21% of air respectively. After these, the next most abundant gases are argon, around 0.9%, and carbon dioxide, about 0.04%. Other gases like neon or helium exist in much smaller amounts, so they don’t rank in the top four. Therefore, the four most abundant gases in dry air are nitrogen, oxygen, argon, and carbon dioxide. The exact order doesn’t matter, so any listing that includes those four is correct.