In the Hoope’s process for refining of aluminium, the fused materials form three different layers and they remain separated during electrolysis also. This is because –

Options

A. There is special arrangement in the cell to keep the layers separate
B. The three layers have different dinsities
C. The three layers are maintained at different temperatures.
D. The upper layer is kept attracted by the cathode and the lower layer is kept attracted by the anode.

Answer

To solve the question regarding the Hoope’s process for refining aluminum and why the fused materials form three different layers that remain separated during electrolysis, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding the Hoope’s Process**:
- The Hoope’s process is a metallurgical method used for refining aluminum. It aims to produce aluminum of very high purity, typically around 99.99%.

2. **Setup of the Process**:
- The process involves an iron container that holds the materials. Inside this container, there are three distinct layers formed during the electrolysis.

3. **Identifying the Layers**:
- The three layers consist of:
- **Top Layer**: This layer contains molten aluminum (Al).
- **Middle Layer**: This layer consists of molten fluorides.
- **Bottom Layer**: This layer contains impure aluminum and is in contact with the anode.

4. **Role of Density**:
- The key reason these layers remain separated during electrolysis is due to their different densities. Each layer has a distinct density, which prevents them from mixing.
- The molten aluminum is less dense than the molten fluorides, allowing it to float on top, while the impure aluminum remains at the bottom.

5. **Conclusion**:
- The separation of the layers is not due to any special arrangement or temperature differences but is fundamentally because of the differences in density among the three layers.

### Final Answer:
The fused materials form three different layers and remain separated during electrolysis because the three layers have different densities.

---