Metallic magnesium is prepared by-

Options

A. Displacement of Mg by iron from `MgSO_(4)` solution
B. Electrolysis of an aqueous solution os `Mg(NO_(3))_(2)`
C. Electrolysis of molten `MgCl_(2)`
D. Reduction of MgO by almunium

Answer

To prepare metallic magnesium, the most common method is through the electrolysis of molten magnesium chloride (MgCl2). Here is a step-by-step solution to the question:

### Step-by-Step Solution:

1. **Identify the Source of Magnesium**:
- Magnesium can be obtained from its compounds, such as magnesium chloride (MgCl2) or magnesium oxide (MgO).

2. **Choose the Method of Preparation**:
- Among the various methods listed, the electrolysis of molten magnesium chloride is the most effective for producing metallic magnesium.

3. **Prepare the Electrolyte**:
- To prepare molten magnesium chloride, you can start with magnesium chloride hexahydrate (MgCl2·6H2O) and remove the water by heating it to obtain anhydrous magnesium chloride (MgCl2).

4. **Set Up Electrolysis**:
- The molten MgCl2 is placed in an electrolytic cell. A graphite rod is typically used as the anode, while the cathode can be made of a conductive material.

5. **Conduct Electrolysis**:
- When an electric current is passed through the molten MgCl2, magnesium ions (Mg²⁺) migrate to the cathode, where they gain electrons (reduction) to form metallic magnesium (Mg).
- At the anode, chloride ions (Cl⁻) lose electrons (oxidation) to form chlorine gas (Cl2).

6. **Collect the Products**:
- The metallic magnesium is collected at the cathode, while chlorine gas is released at the anode.

### Overall Reaction:
The overall reaction during the electrolysis of molten magnesium chloride can be summarized as:
\[ \text{Mg}^{2+} + 2e^- \rightarrow \text{Mg (s)} \quad \text{(at cathode)} \]
\[ 2\text{Cl}^- \rightarrow \text{Cl}_2(g) + 2e^- \quad \text{(at anode)} \]

### Conclusion:
Thus, metallic magnesium is prepared by the electrolysis of molten magnesium chloride.

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