Question

Which noble gas is most abundant in atmospheric dry air?

Answer 1

Hint: You should know that noble gases are the elements present in the 18th group of the periodic table. The most abundant noble gas is the member of the 3rd period of the periodic table.

Complete step by step solution:
-We know that the air around us is a mixture of several gases like nitrogen, oxygen, carbon dioxide and other noble gases.
-Air consists of 78.09 % of nitrogen, 20.95% of oxygen, 0.03% of carbon dioxide. There are other gases too like hydrogen, argon, helium etc.
-One of the components of atmospheric air is the noble gases. They do not constitute a huge percentage and they are present in trace but enough for us to test their presence.
-Before answering the given question, let us discuss the noble gases.
-Noble gases make up a class of chemical elements with similar properties. They are placed in group 18 and are considered as inert elements as they do not react readily due to their stable configuration.
-Under the standard conditions, noble gases are odourless, colourless, with very low chemical reactivity. 
-There are six noble gases in group 18. Those are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the radioactive radon (Rn).
-The noble gases are present in the atmosphere in very small amounts: Percentage of argon is 0.934% and that of neon and helium is 0.0018% and 0.00052% respectively.
We can show the relative abundance in dry air by volume (ppm) of different noble gases as-

Chemical name	Chemical symbol	Abundance by volume (in ppm)
Helium	He	5.24
Neon	Ne	18.18
Argon	Ar	93.40
Krypton	Kr	1.14
Xenon	Xe	0.09
Radon	Rn	traces

We can understand from the above discussion that argon is present in abundance in the atmosphere. 

Therefore, the correct answer is argon.

Note: You should know that air is the primary industrial source of purified argon products. Argon gas is isolated from air by cryogenic fractional distillation. This is a process that also produces purified nitrogen, oxygen, neon, krypton, and xenon gases.
Noble gases have very low boiling and melting points, which makes them useful as cryogenic refrigerants