Use of elecrolysis is not done in :

Options

A. Produce of Na
B. Production of water
C. Purification of metals
D. Production of KOH

Explanation

To solve the question "Use of electrolysis is not done in:", we need to analyze each option provided and determine whether electrolysis is involved in the process described.

### Step-by-Step Solution:

1. **Option 1: Production of Sodium**
- Sodium is produced through the electrolysis of sodium hydroxide (NaOH) in the Kessner process. This process requires high temperatures (above 300°C) to keep sodium hydroxide molten. Therefore, electrolysis is indeed used in the production of sodium.
- **Conclusion:** This option is incorrect as electrolysis is used.

2. **Option 2: Production of Water**
- Water (H₂O) is not produced through electrolysis. Instead, it is typically produced through the reaction of hydrogen gas (H₂) and oxygen gas (O₂) under controlled conditions. Electrolysis can be used to split water into hydrogen and oxygen, but not to produce water itself.
- **Conclusion:** This option is correct as electrolysis is not used in the production of water.

3. **Option 3: Purification of Metals**
- Electrolysis is commonly used for the purification of metals. This process is known as electrolytic refining, where impure metal is made the anode and pure metal is deposited at the cathode.
- **Conclusion:** This option is incorrect as electrolysis is used in the purification of metals.

4. **Option 4: Production of Potassium Hydroxide**
- Potassium hydroxide (KOH) is produced through the electrolysis of potassium carbonate (K₂CO₃) in an aqueous medium. During this process, hydrogen gas is released at the cathode, and carbon dioxide and oxygen gases are evolved at the anode.
- **Conclusion:** This option is incorrect as electrolysis is used in the production of potassium hydroxide.

### Final Answer:
The correct answer is **Option 2: Production of Water**, as electrolysis is not used in this process.