Question

Which is the most plentiful gas in the earth's atmospheric air?

• A. O2
• B. CO2
• C. N2
• D. O3

Hint:

For exams, it's useful to remember the top two gases in the atmosphere by percentage: Nitrogen is number one (approx. 78%), and Oxygen is number two (approx. 21%). Together, they make up 99% of the air.

Answer 1

The Correct Option is C

Step 1: Understanding the Question
The question asks to identify the gas that is most abundant in the Earth's atmosphere.

Step 2: Recalling the Composition of the Atmosphere
The Earth's dry atmosphere is composed of several gases in different proportions. The approximate composition is:


Nitrogen (N2): \textasciitilde 78.08%

Oxygen (O2): \textasciitilde 20.95%

Argon (Ar): \textasciitilde 0.93%

Carbon Dioxide (CO2): \textasciitilde 0.04%

Trace amounts of other gases like Neon, Helium, Methane, Krypton, and Hydrogen. Ozone (O3) is also present in trace amounts, mostly in the stratosphere.


Step 3: Evaluating the Options


(A) O2 (Oxygen): This is the second most plentiful gas.

(B) CO2 (Carbon Dioxide): This is present in very small quantities.

(C) N2 (Nitrogen): This is the most abundant gas, making up about 78% of the atmosphere.

(D) O3 (Ozone): This is a trace gas.


Step 4: Final Answer
Nitrogen (N2) is the most plentiful gas in the Earth's atmosphere. Therefore, option (C) is the correct answer.