Which does not represent correct method ?

Explanation

To determine which method does not represent the correct method for the extraction or purification of metals, we will analyze the methods mentioned in the video transcript step by step.

### Step 1: Analyze the First Method (Kroll Process)
- The Kroll process is used for the extraction of titanium.
- In this method, titanium dioxide (TiO2) is treated with carbon and chlorine to produce titanium tetrachloride (TiCl4).
- Magnesium chloride (MgCl2) is then reduced to magnesium (Mg) through electrolysis.
- Finally, TiCl4 reacts with Mg to yield pure titanium and MgCl2.

**Conclusion:** This method is correct for titanium extraction.

**Hint:** Look for the specific metal associated with each method to determine its validity.

### Step 2: Analyze the Second Method (Mons Process)
- The Mons process is used for the purification of nickel.
- Impure nickel is treated with carbon monoxide to form nickel tetracarbonyl (NiCO4), which is a gaseous compound.
- This compound is unstable and upon heating, it decomposes to yield pure nickel and carbon monoxide.

**Conclusion:** This method is also correct for nickel purification.

**Hint:** Identify the chemical reactions involved and the stability of the products formed.

### Step 3: Analyze the Third Method (Van Arkel Process)
- The Van Arkel process is applicable for the purification of certain metals like titanium, zirconium, hafnium, and silicon.
- In this process, impure metal is treated with iodine vapors to form metal iodide.
- The metal iodide is unstable and upon heating, it decomposes to yield pure metal and liberates iodine, which can be reused.

**Conclusion:** This method is correct for the purification of the specified metals. However, it is incorrectly mentioned for lead.

**Hint:** Check the applicability of the process to the specific metal mentioned.

### Step 4: Identify the Incorrect Method
- The question asks which method does not represent a correct method.
- The Van Arkel process is incorrectly applied to lead, as it is not suitable for lead purification.

**Final Conclusion:** The Van Arkel process (option C) is the incorrect method when applied to lead.

### Summary
The correct methods for the extraction and purification of metals discussed are:
1. Kroll process for titanium - **Correct**
2. Mons process for nickel - **Correct**
3. Van Arkel process for titanium, zirconium, hafnium, and silicon - **Correct**, but **incorrectly applied to lead**.

Thus, the answer is that the Van Arkel process is not a correct method for lead purification.