Although thermodynamically feasible, in practice, magnesium metal is not used for the reduction of alumina in the metallurgy of aluminium. Why ?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Reduction of Alumina:**
- Alumina (Al₂O₃) is the primary source of aluminum metal. The process of reducing alumina to aluminum involves breaking down the aluminum oxide to obtain aluminum.

2. **Thermodynamic Feasibility:**
- The reduction of alumina using magnesium is thermodynamically feasible. This means that the reaction can occur based on the principles of thermodynamics, indicating that it is energetically favorable.

...