Which of the following gases is the most abundant in Earth's atmosphere?

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

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: Nitrogen (N_2), Oxygen (O_2), Argon (Ar), and Carbon dioxide (CO_2), among others in trace amounts.
3. Recognize that Nitrogen (N_2) makes up approximately 78% of the atmosphere by volume, making it the most abundant gas.
4. Oxygen (O_2) is the second most abundant gas, about 21%, followed by Argon (Ar) at roughly 0.93%, and Carbon dioxide (CO_2) at about 0.04%.
5. Therefore, by comparing these percentages, conclude that Nitrogen (N_2) is the most abundant gas in Earth's atmosphere.