Question

Noble gases are adsorbed in :
(A) Anhydrous $ CaC{l_2} $
(B) Charcoal
(C) Conc. $ {H_2}S{O_4} $
(D) Coconut

Answer 1

Hint: Noble gases are inert gases that are present in the atmosphere. They are very less reactive due to its completely filled outer orbital satisfying the octet configuration. They do not participate in chemical bonding since they have very less tendency to donate, accept or share the electrons.

Complete answer:
Noble gases or inert gases are group 18 elements found on the rightmost column of the periodic table. They have an outer electronic configuration $ n{s^2}n{p^6} $ except He, which is $ 1{s^2} $ . The seven noble gases include He, Ne, Ar, Kr, Xe, Rn, Og. They are chemically inert at normal conditions because their outermost orbital has a stable octet configuration.
Adsorption can be defined as the process in which a thin layer of solid, liquid or gas molecules gets adhered to a surface. The molecules that get adhered are called adsorbate and the surface is called adsorbent. It is a surface phenomenon.
Dewar’s Charcoal adsorption method can be used to separate a mixture of noble gases. Here, the adsorption depends on temperature – different gases are adsorbed at different temperature.Lower the atomic mass of the noble gas, lower will be the temperature required to adsorb it. Also, the adsorption capacity of the charcoal depends inversely on temperature. At lower temperature, the adsorption capacity will be more. The activated coconut charcoal is kept in a double-walled flask along with a mixture of noble gases. It can absorb all noble gases except He. It is first kept in a low temperature bath at $ 173\,K $ for a few minutes. Meanwhile, Ar,Kr,Xe which are of higher molecular mass get adsorbed and are collected. Then the charcoal is kept at $ 93\,K $ along with the two unadsorbed gases and later Ne too gets adsorbed leaving He free.
Therefore, the more appropriate answer is (B) charcoal.

Note:
The activated charcoal contains many small pores. This is to increase the surface area for adsorption. As the surface area increases, the rate of adsorption also increases.
Noble gases are monatomic, tasteless, odourless and colourless non-flammable gases at normal conditions. But when they are excited, they emit a characteristic colour of light.