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 determine the correct answer to the question "Use of electrolysis is not done in:", we will analyze each option provided in the context of electrolysis.

### Step-by-Step Solution:

1. **Understanding Electrolysis**:
- Electrolysis is a chemical process that uses direct electric current (DC) to drive a non-spontaneous chemical reaction. It involves two electrodes (anode and cathode) immersed in an electrolyte solution.

2. **Analyzing Each Option**:
- **Option A: Production of Sodium (Na)**:
- Electrolysis is indeed used in the production of sodium. For example, sodium can be produced by the electrolysis of molten sodium chloride (NaCl). Therefore, this option is incorrect regarding the question.

- **Option B: Production of Water**:
- Electrolysis is not used to produce water. Instead, it can be used to decompose water into hydrogen and oxygen gases. Thus, this option is correct as it indicates a process where electrolysis is not utilized for the production of water.

- **Option C: Production of Metal**:
- Electrolysis is widely used for the extraction and purification of metals from their ores. For instance, metals like aluminum and copper are produced through electrolysis. Therefore, this option is also incorrect regarding the question.

- **Option D: Production of KOH**:
- Electrolysis can be used to produce potassium hydroxide (KOH) from potassium chloride (KCl). This means that electrolysis is applicable here as well. Thus, this option is incorrect regarding the question.

3. **Conclusion**:
- Based on the analysis, the correct answer is **Option B: Production of Water**, as electrolysis is not used for producing water.

### Final Answer:
The use of electrolysis is not done in the production of water.