In the extraction of aluminium by Hall-Heroult process purified `Al_(2)O_(3)` is mixed with `CaF_(2)` to

Options

A. lower the melting point of `Al_(3)O_(3)`
B. increase the conductivity of molten mixture
C. reduce `AI^(3+)` into AI(s)
D. acts as catalyst

Explanation

**Step-by-Step Text Solution:**

1. **Understanding the Hall-Heroult Process**: The Hall-Heroult process is the primary method for extracting aluminum from its ore, bauxite. The key raw material used in this process is aluminum oxide (Al₂O₃), which is derived from bauxite.

2. **Role of CaF₂**: In the extraction process, purified Al₂O₃ is mixed with calcium fluoride (CaF₂). The primary purpose of adding CaF₂ is to act as a flux.

3. **Lowering the Melting Point**: The addition of CaF₂ helps to lower the melting point of Al₂O₃. This is important because it allows the electrolysis process to occur at a lower temperature, which reduces energy consumption and makes the process more efficient.

4. **Increasing Conductivity**: CaF₂ also increases the conductivity of the molten mixture. Higher conductivity is crucial for the electrolysis process, as it allows for better flow of electric current through the molten aluminum oxide, facilitating the reduction of aluminum ions to aluminum metal.

5. **Conclusion**: Therefore, the mixing of Al₂O₃ with CaF₂ in the Hall-Heroult process serves to lower the melting point and increase the conductivity of the mixture, making the extraction of aluminum more efficient.

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