Which one of the following processes is used for the manufacturing of calcium ?

Options

A. Reduction with CaO with hydrogen
B. Electrolysis of molten `Ca(OH)_2`
C. Electrolysis of a mixture of anhydrous `CaCl_2 and CaF_2`
D. Reduction of CaO with carbon

Answer

To determine the process used for the manufacturing of calcium, we will analyze the given options step by step.

### Step 1: Understand the Options
The options provided are:
1. Reduction of CaO with hydrogen
2. Electrolysis of molten Ca(OH)₂
3. Electrolysis of a mixture of anhydrous CaCl₂ and CaF₂
4. Reduction of CaO with carbon

### Step 2: Analyze Each Option
- **Option 1: Reduction of CaO with hydrogen**
- This process is not commonly used for calcium production. While it can theoretically produce calcium, it is not the preferred method.

- **Option 2: Electrolysis of molten Ca(OH)₂**
- Electrolysis of calcium hydroxide is not a standard method for producing calcium. It typically yields other products rather than elemental calcium.

- **Option 3: Electrolysis of a mixture of anhydrous CaCl₂ and CaF₂**
- This is a well-known method for producing calcium. The electrolysis of a fused mixture of calcium chloride (CaCl₂) and calcium fluoride (CaF₂) is performed at high temperatures (around 700°C) in an electrolytic cell. The process involves the use of graphite anodes and iron cathodes.

- **Option 4: Reduction of CaO with carbon**
- This method can also produce calcium but is less efficient compared to the electrolysis method.

### Step 3: Identify the Correct Answer
Based on the analysis, the most effective and commonly used method for the manufacturing of calcium is **Option 3: Electrolysis of a mixture of anhydrous CaCl₂ and CaF₂**.

### Final Answer
The correct process used for the manufacturing of calcium is:
**Electrolysis of a mixture of anhydrous CaCl₂ and CaF₂.**

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