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Last updated date: 22nd Nov 2023
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MVSAT Dec 2023

Which‌ ‌is‌ ‌adsorbed‌ ‌in‌ ‌minimum‌ ‌amount‌ ‌by‌ ‌activated‌ ‌charcoal?‌ ‌
(A)‌ ‌‌${H_2}$‌ ‌
(B)‌ ‌‌$C{O_2}$‌ ‌
(C)‌ ‌‌$S{O_3}$‌ ‌
(D)‌ ‌‌$CO$‌

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Hint: Activated charcoal or commonly called as activated carbon is a type of carbon that has been modified to have narrow, limited pores that maximize the available surface area for the process of adsorption or other chemical processes. Adsorption depends closely with the critical temperature of any gas.

Complete answer:
Activated charcoal is made up of tiny black beads or a black porous sponge that is in the form of a solid. Carbon when processed with oxygen turns into what we call the activated charcoal. As a result of the procedure, charcoal that is highly porous gets produced. Because of these tiny openings, the charcoal has a greater surface area.
Adsorption is mostly caused by surface energy. Adsorption is the mechanism by which a given substance accumulates in higher concentrations on the surface of another molecular substance.
It is important for us to note the way of finding the rate of adsorption of each gas;
When a gas has a high critical temperature, it is only because that gas has greater force of attraction or Van Der Waals force between the particles. This increases the adsorption rate of that gas on the surface of activated charcoal.
* The critical temperature rises with the rise in molecular mass. This implies that the gas containing the highest molecular weight will adsorb to a greater extent on the surface of the charcoal. So our aim will be to find the gas having the least molecular weight since that will have the minimum amount of adsorption.
We will take a look at each option and then compute the value of molecular weights and compare all of them to find the one with the minimum weight.
Option (A) ${H_2}$, here the molecular weight of ${H_2} = 1 \times 2 = 2$. This will definitely have a very low amount of adsorption by activated charcoal.
 Option (B) $C{O_2}$, here the molecular mass of $C{O_2} = 12 + 16 \times 2 = 44$. This can have a high amount of adsorption by activated charcoal.
Option (C) $S{O_3}$, here the molecular mass of $S{O_3} = 32 + 16 \times 3 = 80$. This will absolutely have a huge adsorption rate by activated charcoal.
Option (D) $CO$, here the molecular mass of $CO = 12 + 16 = 28$. This can have a good amount of adsorption by activated charcoal.
When we compare the molecular weights of the gases from each option, the gas with the minimum molecular mass is hydrogen (${H_2}$). So we can clearly say that it is the gas that will have a minimum amount of critical temperature so it will have minimum adsorption by activated charcoal.
So evidently options (B), (C) and (D) containing gases $C{O_2}$, $S{O_3}$ and $CO$ respectively are incorrect options, since ${H_2}$ is the correct gas.
Therefore the final answer for the gas having minimum adsorption by the activated charcoal will be option (A) ${H_2}$.

One significant industrial use for the activated charcoal is its use in metal finishing, mainly purifying electroplating solutions. It is, for example, the primary purification method for bright nickel plating solutions that have organic impurities which need to be removed. Activated carbon treatment is able to eliminate the unnecessary particles produced as a result of direct current penetration into plating solutions and thereby enhances the plating efficiency to the standard required.