The chemical treatment of the ore for concentration is done in the case of :

Options

A. aluminium
B. silver
C. copper
D. gold

Answer

To solve the question regarding the chemical treatment of ore for concentration, we will analyze each of the given options: Aluminum, Silver, Copper, and Gold.

### Step-by-Step Solution:

1. **Understanding Concentration of Ore**:
- Concentration of ore is the process of removing impurities from the ore to obtain a purer form of the desired metal. This can be done through physical methods or chemical methods (leaching).

2. **Analyzing Aluminum**:
- The ore of Aluminum is Bauxite.
- The extraction involves treating Bauxite with Sodium Hydroxide (NaOH) at high temperatures (473 to 523 K), which leads to the formation of sodium methaaluminate.
- This process is a chemical treatment, thus Aluminum involves chemical treatment for concentration.

3. **Analyzing Silver**:
- Silver is extracted using the cyanide process, where impure silver is treated with sodium cyanide in the presence of water and oxygen to form a soluble complex.
- This complex is then treated with zinc to obtain pure silver.
- Therefore, Silver also involves chemical treatment for concentration.

4. **Analyzing Copper**:
- Copper is extracted from its ore (like Copper carbonate) through a process called calcination, which involves heating the ore to convert it into copper oxide.
- This process does not involve leaching or chemical treatment in the same way as Aluminum or Silver, so Copper does not qualify.

5. **Analyzing Gold**:
- Gold is also extracted using the cyanide process, similar to Silver. Impure gold is treated with sodium cyanide and forms a soluble complex, which is then reduced to obtain pure gold.
- Thus, Gold also involves chemical treatment for concentration.

6. **Conclusion**:
- Based on the analysis, the metals that undergo chemical treatment for concentration are Aluminum, Silver, and Gold. Copper does not undergo chemical treatment for concentration.

### Final Answer:
The chemical treatment of the ore for concentration is done in the case of **Aluminum, Silver, and Gold**.

---