Electro refining which is based on phenomenon of Electrolysis where

Options

A. impure metal is made anode and pure metal is cathode
B. impure metal is cathode and pure metal is anode
C. pure metal makes both anode and cathode
D. none of the above

Explanation

### Step-by-Step Solution:

1. **Understanding Electro Refining**:
- Electro refining is a method used to purify metals, primarily copper. It is based on the principle of electrolysis.

2. **Components of Electrolysis**:
- In the electrolysis process, there are two main electrodes: the anode and the cathode.
- The anode is made up of the crude (impure) metal, while the cathode is a thin sheet of pure metal.

3. **Electrolyte**:
- The electrolyte used in this process is a soluble solution of the same metal that is being refined.

4. **Oxidation at the Anode**:
- When electricity is passed through the system, the impure metal at the anode undergoes oxidation. This means that the metal atoms lose electrons and dissolve into the solution as metal ions.

5. **Reduction at the Cathode**:
- Meanwhile, at the cathode, reduction occurs. The metal ions from the solution gain electrons and are deposited as pure metal on the cathode.

6. **Settling of Impurities**:
- The impurities that were present in the crude metal do not dissolve into the solution and instead settle down at the bottom of the electrolytic cell as the anode gradually dissolves.

7. **Conclusion**:
- In summary, during electro refining, the impure metal at the anode is oxidized to metal ions, which then move to the cathode where they are reduced and deposited as pure metal. The impurities settle below the anode.