Which gas is most abundant in Earth's atmosphere?

• A. Water vapor
• B. Oxygen
• C. Nitrogen
• D. Carbon dioxide

Answer: (C)

Verified step by step guidance

1. Understand that Earth's atmosphere is composed of several gases, each present in different proportions.
2. Recall the major components of dry air: primarily nitrogen (N\_2), oxygen (O\_2), argon (Ar), and carbon dioxide (CO\_2), with water vapor (H\_2O) varying depending on humidity.
3. Recognize that nitrogen makes up about 78% of the Earth's atmosphere by volume, making it the most abundant gas.
4. Note that oxygen is the second most abundant gas, approximately 21%, while carbon dioxide and water vapor are present in much smaller amounts.
5. Conclude that among the options given, nitrogen is the most abundant gas in Earth's atmosphere.