Extraction of aluminium from bauxite ore, reduction is carried out by :

Options

A. carbon
B. magnesium
C. electrolysis
D. hydrogen

Answer

To solve the question regarding the extraction of aluminum from bauxite ore, we will follow these steps:

### Step 1: Identify the Ore
The primary ore of aluminum is bauxite, which is chemically represented as \( \text{Al}_2\text{O}_3 \cdot 2\text{H}_2\text{O} \).

### Step 2: Understand the Extraction Process
The extraction of aluminum from bauxite involves a reduction process. The common method used for this extraction is electrolysis.

### Step 3: Electrolytic Process
In the electrolytic process, bauxite is first converted into aluminum oxide (\( \text{Al}_2\text{O}_3 \)). This aluminum oxide is then dissolved in molten cryolite (\( \text{Na}_3\text{AlF}_6 \)) to lower the melting point and improve conductivity.

### Step 4: Set Up Electrodes
In the electrolytic cell, there are two electrodes:
- **Anode**: Made of graphite, where oxidation occurs.
- **Cathode**: Where aluminum is deposited.

### Step 5: Reactions at Electrodes
At the anode, the oxidation reaction occurs:
\[ \text{C} + 2\text{O}^{2-} \rightarrow \text{CO}_2 + 4\text{e}^- \]
At the cathode, the reduction reaction occurs:
\[ 2\text{Al}^{3+} + 6\text{e}^- \rightarrow 2\text{Al} \]

### Step 6: Conclusion
Based on the above steps, the reduction of aluminum from bauxite ore is carried out by the process of electrolysis. Thus, the correct answer is option 3: electrolysis.

### Summary of Steps:
1. Identify the ore (bauxite).
2. Understand the extraction process (electrolysis).
3. Describe the electrolytic process (using molten cryolite).
4. Set up electrodes (anode and cathode).
5. Write the reactions occurring at the electrodes.
6. Conclude with the correct method of extraction.