Question

The most abundant gas found in the earth atmosphere is :

• A. \(\text{CO}_2\)
• B. \(\text{O}_2\)
• C. \(\text{CH}_4\)
• D. \(\text{N}_2\)

Hint:

Remember the top two gases in Earth's atmosphere: 1. {Nitrogen (\(\text{N}_2\))} \(\approx\) 78% (Most abundant) 2. {Oxygen (\(\text{O}_2\))} \(\approx\) 21% These two make up about 99% of the dry air.

Answer 1

The Correct Option is D

Concept: Earth's atmosphere is a mixture of several gases. The relative amounts of these gases determine which one is the most abundant. Step 1: Composition of Earth's Dry Atmosphere (Approximate Percentages by Volume)
Nitrogen (\(\text{N}_2\)): About 78.08%
Oxygen (\(\text{O}_2\)): About 20.95%
Argon (Ar): About 0.93%
Carbon Dioxide (\(\text{CO}_2\)): About 0.04% (variable, but this is a typical current value)
Other gases (Neon, Helium, Methane (\(\text{CH}_4\)), Krypton, Hydrogen, etc.): Trace amounts, collectively less than 0.01%. Water vapor is also a significant component of the atmosphere, but its concentration is highly variable (0-4%). The question usually refers to the composition of dry air. Step 2: Identifying the most abundant gas From the percentages, Nitrogen (\(\text{N}_2\)) is clearly the most abundant gas, making up roughly 78% of the Earth's atmosphere. Oxygen (\(\text{O}_2\)) is the second most abundant. Step 3: Evaluating the options
(1) \(\text{CO}_2\) (Carbon Dioxide): Present in a small percentage (\(\sim 0.04%\)).
(2) \(\text{O}_2\) (Oxygen): Second most abundant (\(\sim 21%\)).
(3) \(\text{CH}_4\) (Methane): Present in trace amounts (parts per million).
(4) \(\text{N}_2\) (Nitrogen): Most abundant (\(\sim 78%\)). Therefore, Nitrogen (\(\text{N}_2\)) is the most abundant gas in Earth's atmosphere.