Question

Among \(Fe^{3+}, Pb^{2+}, Cu^{2+}\) and \(Mn^{2+}\), identify the one that gets precipitated out while passing \(H_2S\) in presence of \(NH_4OH\) as group reagent. The highest possible oxidation state of the corresponding metal is:

• A. +3
• B. +4
• C. +2
• D. +7

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
In qualitative inorganic analysis, different cations are precipitated in specific groups using specific reagents. \(H_2S\) in the presence of \(NH_4OH\) (alkaline medium) is the reagent for Group IV cations.

Step 3: Detailed Explanation:
- Group II (\(Pb^{2+}, Cu^{2+}\)): Precipitated as sulphides in acidic medium (\(H_2S/HCl\)).
- Group III (\(Fe^{3+}\)): Precipitated as hydroxides using \(NH_4OH + NH_4Cl\).
- Group IV (\(Mn^{2+}, Zn^{2+}, Ni^{2+}, Co^{2+}\)): Precipitated as sulphides in basic medium (\(H_2S + NH_4OH\)).
The metal that fits the condition is Manganese (\(Mn\)).
The highest possible oxidation state of Manganese is +7 (as seen in \(KMnO_4\) or \(Mn_2O_7\)).

Step 4: Final Answer:
The highest oxidation state of the metal (Mn) is +7.