Which of the following oxides cannot be reduced with carbon to obtain the metal ?

Options

A. `MnO_(2)`
B. `Cr_(2)O(3)`
C. `Al_(2)O_(3)`
D. None of these

Explanation

To determine which of the following oxides cannot be reduced with carbon to obtain the metal, we need to analyze the affinity of the oxides for oxygen compared to carbon.

### Step-by-Step Solution:

1. **Identify the Oxides**: The oxides given in the question are MnO2 (Manganese dioxide), Cr2O3 (Chromium trioxide), and Al2O3 (Aluminum oxide).

2. **Understand Reduction with Carbon**: In metallurgy, carbon is often used as a reducing agent to extract metals from their oxides. This process involves the removal of oxygen from the metal oxide, allowing the metal to be obtained.

3. **Check Affinity for Oxygen**: For an oxide to be reducible with carbon, the metal in the oxide must have a lower affinity for oxygen than carbon. If the metal has a higher affinity for oxygen, it will not be reduced by carbon.

4. **Analyze Each Oxide**:
- **MnO2**: Manganese has a moderate affinity for oxygen, and it can be reduced by carbon.
- **Cr2O3**: Chromium also has a moderate affinity for oxygen, and it can be reduced by carbon.
- **Al2O3**: Aluminum oxide has a very high affinity for oxygen, making it difficult to reduce with carbon.

5. **Conclusion**: Among the given oxides, Al2O3 (Aluminum oxide) cannot be reduced with carbon due to its high affinity for oxygen.

### Final Answer:
The oxide that cannot be reduced with carbon to obtain the metal is **Al2O3 (Aluminum oxide)**.

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