Which gas is most abundant in Earth's atmosphere?

• A. Argon (Ar)
• B. Oxygen (O_2)
• C. Nitrogen (N_2)
• D. Carbon dioxide (CO_2)

Answer: (C)

Verified step by step guidance

1. Understand that Earth's atmosphere is composed of several gases, each with a different abundance by volume.
2. Recall the major components of dry air and their approximate percentages: Nitrogen (N\_2), Oxygen (O\_2), Argon (Ar), and Carbon dioxide (CO\_2).
3. Recognize that Nitrogen (N\_2) makes up about 78% of the atmosphere, making it the most abundant gas.
4. Note that Oxygen (O\_2) is the second most abundant gas, roughly 21%, followed by Argon (Ar) at about 0.93%, and Carbon dioxide (CO\_2) at approximately 0.04%.
5. Conclude that among the given options, Nitrogen (N\_2) is the correct answer as the most abundant gas in Earth's atmosphere.