Arrange the following gases in increasing (lower to higher) order of their mixing ratio (%) in the atmosphere:
(A) Helium (He) (B) Hydrogen (H₂) (C) Krypton (Kr) (D) Xenon (Xe) (E) Neon (Ne)
Choose the correct answer:

Correct option is D

The correct answer is (4) D, B, C, A, E. The mixing ratio of atmospheric gases refers to the abundance of these gases relative to the total volume of air. In this case, we need to arrange the gases based on their increasing mixing ratio (from lowest to highest):
1. Xenon (Xe)
· Mixing Ratio: 0.087 ppm (Parts per million). It is the least abundant among the listed gases.
2. Hydrogen (H₂)
· Mixing Ratio: 0.5 ppm. Present in trace amounts, primarily from biological and chemical processes.
3. Krypton (Kr)
· Mixing Ratio: 1.14 ppm. An inert gas present in small quantities in the atmosphere.
4. Helium (He)
· Mixing Ratio: 5.24 ppm. Lightweight and found mostly in the upper atmosphere due to its low molecular weight.
5. Neon (Ne)
· Mixing Ratio: 18.18 ppm. More abundant than the other noble gases in the atmosphere.
Hence, the correct order of increasing mixing ratio is D (Xenon), B (Hydrogen), C (Krypton), A (Helium), E (Neon).
Information Booster:
1. Xenon (Xe):
· The heaviest noble gas found in trace amounts, used in lighting and anesthesia.
2. Hydrogen (H₂):
· The lightest element, used in industrial applications and as a clean fuel source.
3. Krypton (Kr):
· Used in lighting (e.g., high-intensity lamps) and photography.
4. Helium (He):
· Important for cooling in cryogenics and used in balloons and airships.
5. Neon (Ne):
· Known for its bright red-orange glow in neon signs and lighting applications.
Additional Knowledge:
· Mixing Ratio:
· The ratio of the mass or volume of a specific gas to the mass or volume of dry air.
· Noble Gases:
· Inert gases that do not easily form compounds due to their stable electron configurations.
· Atmospheric Abundance:
· The concentration of noble gases decreases progressively from Neon to Xenon.