Question

Arrange the following gases in descending order in terms of percentage in dry air of the lower atmosphere.
(A) Carbon dioxide
(B) Argon
(C) Nitrogen
(D) Oxygen
Choose the correct answer from the options given below:

• A. (D), (C), (A), (B)
• B. (C), (A), (D), (B)
• C. (C), (D), (A), (B)
• D. (C), (D), (B), (A)

Answer 1

The Correct Option is D

To determine the descending order of gases by percentage in dry air of the lower atmosphere, consider these approximate values: Nitrogen (N₂) makes up about 78.08% of the atmosphere, Oxygen (O₂) accounts for approximately 20.95%, Argon (Ar) is about 0.93%, and Carbon Dioxide (CO₂) is roughly 0.04% of the atmosphere.
Here is the order of the gases based on their percentage concentrations: 

• Nitrogen (C) - 78.08%
• Oxygen (D) - 20.95%
• Argon (B) - 0.93%
• Carbon Dioxide (A) - 0.04%

Thus, the correct descending order of these gases by their percentage in dry air is: (C), (D), (B), (A).

Answer 2

The correct answer is (4) (C), (D), (B), (A).

Here’s the reasoning behind the arrangement of gases in descending order of percentage in dry air of the lower atmosphere:

(C) Nitrogen: Nitrogen makes up about 78% of the Earth's atmosphere, making it the most abundant gas in dry air.

(D) Oxygen: Oxygen is the second most abundant gas, comprising about 21% of the Earth's atmosphere.

(B) Argon: Argon is present in much smaller quantities, around 0.93% of the Earth's atmosphere.

(A) Carbon Dioxide: Carbon dioxide is present in trace amounts, approximately 0.04% or 400 ppm (parts per million), but its concentration can vary.

Thus, the correct order of gases from highest to lowest percentage is: (C) Nitrogen, (D) Oxygen, (B) Argon, and (A) Carbon dioxide.

So, the correct answer is (4) (C), (D), (B), (A).