In which of the following processes, fused sodium hydroxide is electrolysed at a `333^(@)C` temperature for extraction of sodium

Options

A. Castner process
B. Cyanide process
C. Down's process
D. Both (2) & (3)

Answer

To solve the question regarding the process in which fused sodium hydroxide is electrolyzed at a temperature of 333°C for the extraction of sodium, we will analyze each of the provided options step by step.

### Step-by-Step Solution:

1. **Understanding the Question**:
- The question asks which process involves the electrolysis of fused sodium hydroxide at 333°C to extract sodium.

2. **Analyzing the Options**:
- **Option A: Castner Process**:
- The Castner process, also known as the Castner-Kelliner process, is specifically used for the extraction of sodium metal through the electrolysis of molten sodium hydroxide at approximately 330°C. This matches the conditions described in the question.

- **Option B: Cyanide Process**:
- The cyanide process (or MacArthur-Forrest process) is used for the extraction of precious metals like gold and silver from their ores using sodium cyanide. This process does not involve sodium extraction from sodium hydroxide, making it incorrect for this question.

- **Option C: Downs Process**:
- The Downs process is an electrochemical method used for the commercial preparation of magnesium metal from molten magnesium chloride. This process does not involve sodium hydroxide and is therefore not relevant to the extraction of sodium.

- **Option D: Both B and C**:
- Since both the cyanide process and the Downs process do not involve the extraction of sodium from sodium hydroxide, this option is also incorrect.

3. **Conclusion**:
- Based on the analysis of the options, the correct process for the extraction of sodium from fused sodium hydroxide at 333°C is the **Castner Process**.

### Final Answer:
The correct answer is **Option A: Castner Process**.

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