It is true that under certain condition, Mg can reduce `Al_2O_3` and Al can reduce `MgO`? What are those conditions?

Explanation

To determine the conditions under which magnesium (Mg) can reduce aluminum oxide (Al₂O₃) and aluminum (Al) can reduce magnesium oxide (MgO), we can refer to the Ellingham diagram, which illustrates the stability of metal oxides at varying temperatures.

### Step-by-Step Solution:

1. **Understanding the Ellingham Diagram**:
- The Ellingham diagram plots the Gibbs free energy change (ΔG) for the formation of oxides as a function of temperature. The lower the ΔG, the more stable the oxide.

2. **Reduction of Al₂O₃ by Mg**:
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