Choose the most appropriate answer from the options given below :
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Mnemonic for Groups:
Group II (Acidic Sulfide): "Pass (Pb) His (Hg) Cup (Cu) Back (Bi) Soon (Sn) As (As) Sab (Sb) Cadet (Cd)".
Group IV (Basic Sulfide): "Zinda (Zn) Munni (Mn) Nek (Ni) Co (Co)".
Step 1: Understanding the Concept:
In qualitative inorganic analysis, metal cations are separated into groups based on their ability to precipitate with specific reagents under controlled pH conditions. Step 2: Detailed Explanation:
Let's analyze the groups for each given ion:
1. Group II: Cations precipitated as sulfides in acidic medium (\(\text{H}_2\text{S} + \text{dil. HCl}\)).
- Group IIA (Copper Group): Includes \(\text{Pb}^{2+}\), \(\text{Hg}^{2+}\), \(\text{Cu}^{2+}\), \(\text{Cd}^{2+}\), \(\text{Bi}^{3+}\). Their sulfides are insoluble in yellow ammonium sulfide. Thus, (c) \(\rightarrow\) (ii).
- Group IIB (Arsenic Group): Includes \(\text{As}^{3+}\), \(\text{Sb}^{3+}\), \(\text{Sn}^{4+}\). Their sulfides are soluble in yellow ammonium sulfide. Thus, (b) \(\rightarrow\) (iv).
2. Group III: Cations precipitated as hydroxides in the presence of \(\text{NH}_4\text{Cl}\) and \(\text{NH}_4\text{OH}\). Includes \(\text{Fe}^{3+}\), \(\text{Cr}^{3+}\), and \(\text{Al}^{3+}\). Thus, (d) \(\rightarrow\) (i).
3. Group IV: Cations precipitated as sulfides in basic medium (\(\text{H}_2\text{S} + \text{NH}_4\text{Cl} + \text{NH}_4\text{OH}\)). Includes \(\text{Zn}^{2+}\), \(\text{Mn}^{2+}\), \(\text{Ni}^{2+}\), \(\text{Co}^{2+}\). Thus, (a) \(\rightarrow\) (iii). Step 3: Final Answer:
The matching is: (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i). This corresponds to option (C).
