Question

Group reagent for analytic group \[IV\] is :
(A) \[N{H_4}Cl + N{H_4}OH\]
(B) \[N{H_4}Cl + N{H_4}OH + {H_2}S\]
(C) \[N{H_4}OH + {(N{H_4})_2}C{O_3}\]
(D) \[HCl + {H_2}S\]

Answer 1

Hint: The Group Reagent is a mixture of reagents that serves as a preliminary indication of a particular cation. A positive test result is shown by the precipitation of a material, while a negative test result is indicated by the absence of precipitation. They can be separated from the solution using a reagent that each group shares.

Complete Step by Step Solution:
Group reagent refers to the substance that is used to identify a collection of radicals. While the cationic portion of salt is referred to as the basic radical, the anionic portion is known as the acid radical. All of the fundamental radicals are broken down into various groups for the salt analysis.

We now understand that the group reagents are a collection of reagents used to detect the fundamental radical (cation) in a specific salt. The basic radicals of various groups can be identified using various sets of reagents.

In group \[I\], cations are silver, lead, and mercury\[(I)\]—and to ascertain which of these ions are present and which are not, a mysterious solution must be used.

Now, let’s see the categories of the group \[II\] in which, the cations are \[P{b^{2 + }},C{u^{2 + }}\;\] and group reagent is \[{H_2}S\] in the presence of \[dil.\,HCl.\]
Similarly, consider the group \[III\] ,
In group \[III\] , the cations are \[F{e^{3 + }},A{l^{3 + }}\;\] and group reagent is \[N{H_4}OH\]in the presence of \[N{H_4}Cl\].
And, in group \[IV\], cations are \[N{i^{2 + }},C{o^{2 + }}\;\] and group reagent is \[{H_2}S\]in the presence of \[N{H_4}OH\].
Therefore, \[N{H_4}Cl + N{H_4}OH + {H_2}S\]is a group reagent for analytic group \[IV\].
Thus, the correct option is: (B) \[N{H_4}Cl + N{H_4}OH + {H_2}S\].

Note: Since ammonium is a non-metallic cation and possesses a variety of testing reagents, ammonium ions are members of the zero group. As a result, \[NH_4^ + \] is examined first, remaining in the zero group. Ammonium hydroxide in the presence of ammonium chloride serves as the group reagent. In order to prevent the fourth and fifth group radicals from precipitating as their insoluble hydroxides, which have substantially higher solubility products, \[N{H_4}Cl\]is added to prevent the ionisation of \[N{H_4}OH\].