Which noble gas is not found in the atmosphere?
- AOption (a)
Argon
- BOption (b)
Krypton
- COption (c)
Xenon
- DOption (d)
Radon
हिंदी में देखें
वायुमंडल में कौन सी निष्क्रिय गैस नहीं पाई जाती है?
- (a)
आर्गन
- (b)
क्रिप्टॉन
- (c)
जिनान
- (d)
रैडॉन
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Correct answer
Radon
Why this answer is correct
The correct answer is Radon.
- In the modern periodic table, group 18 belongs to noble gases.
- This group of a series of gases includes:
- Argon. Helium, Neon, Krypton, Xenon, and Radon.
- Radon is the only radioactive out of all and it's also not present in the Atmosphere.
| Noble Gas | Percentage (%) | Relative Abundance to other components of Atmosphere |
|---|---|---|
| Helium | 0.00052 | 7th |
| Neon | 0.0018 | 6th |
| Argon | 0.934 | 4th |
| Krypton | 0.0001 | 9th |
| Xenon | 0.000009 | 15th |
Important Points
- Their outer shell of valence electrons is considered to be "full", giving them little tendency to participate in chemical reactions, so they are considered the most stable elements of the periodic table.
- Noble gases are also known as inert and rare gases.
- Neon, argon, krypton, and xenon are obtained from air in an air separation unit using the methods of liquefaction of gases and fractional distillation.
- Helium is sourced from natural gas fields that have high concentrations of helium in natural gas, using cryogenic gas separation techniques.
- Radon is usually isolated from the radioactive decay of dissolved radium, thorium, or uranium compounds.
Key Points
- Nobel gases are odourless, non-flammable, colourless, and monoatomic gas with low chemical reactivity.
- All noble gases are insoluble in water.
- Nobel gases conduct electricity and fluorescence which can be needed in many conditions to maintain a constant and safe environment.
- They have a complete octet that makes them very stable, so they hardly react with other elements. Xenon is the only noble gas that may form compounds either with fluoride or oxide.
Additional Information
- Noble gases have several important applications in industries such as lighting, welding, and space exploration.
- Helium-oxygen breathing gas is often used by deep-sea divers at depths of seawater over 55 m (180 ft).
- After the risks caused by the flammability of hydrogen became apparent, it was replaced with helium in blimps and balloons.









