If `NH_(4)OH` in presence of `NH_(4)Cl` is added to a solution containing `Al_(2)(SO_(4))_(2) and MgSO_(4)`, which of the following will precipitate?

Options

A. `Al(OH)_(3)` only
B. `Mg(OH)_(2)` only
C. `Al(OH)_(3) and Mg(OH)_(2)`
D. None of these

Answer

To solve the problem of determining which compound will precipitate when `NH₄OH` (ammonium hydroxide) in the presence of `NH₄Cl` (ammonium chloride) is added to a solution containing `Al₂(SO₄)₃` (aluminum sulfate) and `MgSO₄` (magnesium sulfate), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Group Reagents**:
- Ammonium hydroxide (`NH₄OH`) and ammonium chloride (`NH₄Cl`) are group reagents for the third group of cations in qualitative analysis.

2. **Identify the Cations Present**:
- The solution contains two cations: aluminum ions (`Al³⁺`) from aluminum sulfate and magnesium ions (`Mg²⁺`) from magnesium sulfate.

3. **Determine the Group of Each Cation**:
- Aluminum (`Al³⁺`) belongs to the third group of cations.
- Magnesium (`Mg²⁺`) belongs to the sixth group of cations.

4. **Precipitation Reaction**:
- When `NH₄OH` is added to a solution containing `Al³⁺`, it reacts to form aluminum hydroxide (`Al(OH)₃`), which is a white precipitate.
- Magnesium ions (`Mg²⁺`), however, do not precipitate with ammonium hydroxide in this context, as they remain soluble.

5. **Conclusion**:
- Therefore, the only precipitate formed in this reaction is aluminum hydroxide (`Al(OH)₃`).

### Final Answer:
- The precipitate formed is **Aluminum Hydroxide (Al(OH)₃)**.