Which of the following metals is protected even by a layer of its oxide?

Options

A. Copper
B. Silver
C. Iron
D. Aluminium

Explanation

To determine which metal is protected even by a layer of its own oxide, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Oxide Layers**: Some metals can form a protective oxide layer when exposed to air or moisture. This layer can prevent further oxidation and corrosion of the underlying metal.

2. **Identifying the Metal**: Among various metals, we need to identify which one forms a stable and protective oxide layer.

3. **Considering Aluminum**: Aluminum is known to be a highly reactive metal. When exposed to air or water, it reacts to form aluminum oxide (Al2O3).

4. **Formation of Passive Layer**: The aluminum oxide (Al2O3) forms a thin, passive layer on the surface of aluminum. This layer is adherent and prevents further oxidation of the aluminum beneath it.

5. **Conclusion**: Since aluminum is protected from further corrosion by its own oxide layer (Al2O3), it is the correct answer to the question.

### Final Answer:
The metal that is protected even by a layer of its oxide is **Aluminum (Al)**.

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