Aluminium is prepared in large quantities by

Options

A. heating cryolite in a limited quantity of air
B. reducing aluminium oxide with coke.
C. reducing aluminium oxide with sodium.
D. electrolysing aluminium oxide dissolved in fused electrolyte

Explanation

To prepare aluminum in large quantities, the following steps are involved:

### Step-by-Step Solution:

1. **Understanding the Source Material**:
Aluminum is primarily extracted from bauxite ore, which contains aluminum oxide (Al₂O₃).

**Hint**: Identify the main ore from which aluminum is derived.

2. **Processing Bauxite**:
The bauxite is refined to obtain aluminum oxide (alumina). This is typically done through the Bayer process, where bauxite is treated with sodium hydroxide to produce alumina.

**Hint**: Know the process used to convert bauxite into aluminum oxide.

3. **Electrolytic Reduction**:
The aluminum oxide is then dissolved in a fused electrolyte, which typically includes cryolite (Na₃AlF₆) and sometimes calcium fluoride (CaF₂). This mixture lowers the melting point of aluminum oxide and increases its electrical conductivity.

**Hint**: Remember the role of cryolite and other materials in the electrolytic process.

4. **Electrolysis**:
The dissolved aluminum oxide is subjected to electrolysis. An electric current is passed through the solution, causing the aluminum ions to migrate to the cathode where they are reduced to form aluminum metal, while oxygen is released at the anode.

**Hint**: Understand the electrolysis process and the movement of ions during this reaction.

5. **Collection of Aluminum**:
The aluminum metal produced sinks to the bottom of the electrolytic cell and can be periodically removed.

**Hint**: Know how the aluminum is collected after the electrolysis process.

6. **Yield**:
From approximately 4 to 5 tons of bauxite, about 2 tons of alumina can be produced, which yields approximately 1 ton of pure aluminum after the electrolytic reduction.

**Hint**: Be aware of the efficiency of the process in terms of raw material to product ratio.

### Final Answer:
Aluminum is prepared in large quantities by **electrolyzing aluminum oxide dissolved in a fused electrolyte**.

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