The correct descending sequence of the constituent gases in terms of volume percentage is option 2: 1-4-2-3.

Let`s dissect each option to understand why option 2 is the correct answer:

Option 1 (1-3-2-4): This sequence suggests that Argon has the highest volume percentage followed by Helium, Neon, and finally Carbon dioxide. However, this is incorrect because Argon is actually present in the atmosphere in a much smaller volume than Helium.

Option 2 (1-4-2-3): This sequence correctly represents the descending order of the constituent gases. Argon has the highest volume percentage, followed by Carbon dioxide, then Neon, and finally Helium.

Option 3 (4-2-3-1): This sequence suggests that Carbon dioxide has the highest volume percentage, followed by Neon, Helium, and finally Argon. This is incorrect because Carbon dioxide is actually present in much smaller volume compared to Argon.

Option 4 (2-4-1-3): This sequence suggests that Neon has the highest volume percentage followed by Carbon dioxide, Argon, and finally Helium. However, this is incorrect because Neon is present in the atmosphere in a much smaller volume than both Argon