How many metals are commercially reduced by Goldschmidt's aluminothermic process from the given metals ?
`Na, Pb, Al, Mn, Sn`.

Explanation

To determine how many metals from the given list are commercially reduced by Goldschmidt's aluminothermic process, we will analyze each metal one by one.

### Step-by-Step Solution:

1. **Identify the Metals**: The metals given are Sodium (Na), Lead (Pb), Aluminium (Al), Manganese (Mn), and Tin (Sn).

2. **Analyze Sodium (Na)**:
- Sodium is extracted from rock salt (NaCl) through electrolysis, not by the aluminothermic process.
- **Conclusion**: Sodium is not reduced by the aluminothermic process.

3. **Analyze Lead (Pb)**:
- Lead is primarily extracted from its sulfide ore (PbS) using self-reduction, where it is converted to lead oxide and then reduced to lead.
- **Conclusion**: Lead is not reduced by the aluminothermic process.

4. **Analyze Aluminium (Al)**:
- Aluminium is extracted from bauxite ore using the Bayer process followed by electrolytic refining. Although aluminium is involved in the aluminothermic process, it is not reduced by it; rather, it is produced through electrolysis.
- **Conclusion**: Aluminium is not reduced by the aluminothermic process.

5. **Analyze Manganese (Mn)**:
- Manganese is extracted from its oxide ore using aluminium as a reducing agent in the aluminothermic process. The reaction involves aluminium displacing manganese from its oxide.
- **Conclusion**: Manganese is reduced by the aluminothermic process.

6. **Analyze Tin (Sn)**:
- Tin is typically extracted from its oxide using carbon as a reducing agent, not aluminium.
- **Conclusion**: Tin is not reduced by the aluminothermic process.

7. **Final Count**:
- From the analysis, only Manganese is reduced by the Goldschmidt's aluminothermic process.
- Therefore, the total number of metals reduced by this process from the given list is **1**.

### Final Answer:
Only **1 metal (Manganese)** is commercially reduced by Goldschmidt's aluminothermic process from the given metals.

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