Question

what is the rarest gas on earth?

Answer 1

Hint: Noble gases are chemically unreactive and exist in monatomic state. These gases are also called inert gas. Among the 118 elements present in the periodic table, only noble elements exist in gaseous state.

Complete answer:
Among the 118 elements present in the periodic table, only noble elements exist in gaseous state. These elements belong to group 18 and have complete octet. Group number 18 elements includes Helium \[(He)\], Neon \[(Ne)\], Argon \[(Ar)\], Krypton \[(Kr)\], Xenon \[(Xe)\] and Radon \[(Rn)\] . Amongst these gases, Xenon gas is the rarest gas present on the earth. Air contains only 0.000009 % of xenon. Hence it is used only when other alternative lighter gases are not available. Apart from Xenon, neon and Krypton are present in 0.0018 and 0.00011 % respectively. The applications of xenon gas include in making car headlights, semiconductors, plasma screens and flash cameras. Besides, xenon has medicinal applications also which includes its anaesthetic property.

Additional information:
Because of complete octet, noble gases are not capable of losing or gaining electrons, that's why these are chemically inert and are also called inert gases. The physical properties of noble gases include colourless, odourless and non-inflammable in nature. The other uses of noble gases includes helium is used in filling balloons

Note:
It is important to note that Xenon gas is the rarest gas present on the earth. Air contains only 0.000009 % of xenon. Other noble gases such as neon and Krypton are present in 0.0018 and 0.00011 % respectively.