Question

The inert gas abundantly found in atmosphere is:
A.\[Kr\]
B.$He$
C.$Ar$
D.$Xe$

Answer 1

Hint: Inert gas is gas that does not usually react chemically with other elements. They are also known as noble gas but all noble gases are not inert. Noble gases are present in the Group $18$ of the periodic table which are- helium$(He)$, neon$(Ne)$, argon$(Ar)$, krypton$(Kr)$, xenon$(Xe)$ and radon $(Ra)$.

Complete answer:
Noble gases are inert but all noble gases are not inert. Noble gases are highly stable due to their completely filled outermost shell with eight electrons and are not able to react with other compounds. These gases constitute a major part in the atmosphere and are easily available.
Nitrogen composition in air is about $78.3\% $ and acts as an inert gas (example of the statement which says all noble gases are inert but all inert gases are not noble), and the most abundantly found inert is argon which constitutes about $1\% $ of the atmospheric air.
Therefore, option (c) $Ar$ is the inert gas that is found abundantly in the atmosphere.

Note:
Noble gases usually do not make compounds with other elements with the exception of Xenon which reacts with fluorine and oxygen. Due to its large size it does not have a good hold of electrons that are present in the outermost shell and is able to form compounds with high electronegative and small sized elements like oxygen and fluorine.