The decay of metals by atmospheric oxygen and moisture is called corrosion. Few metals do not react with atmospheric gases and water and do not undergo corrosion, while others develop a dull layer on them or a coloured layer to spoil their shiny appearance or turn black or are converted into powder. few elements, on the other hand are protected due to presence of this dull layer of oxide on them.
Q. Aluminium does not react readily with air or water because

Options

A. it occupies high position in electrochemical series.
B. it lies below hydrogen in electrochemical series
C. it is covered with a layer of oxide which does not rub off.
D. it is a noble metal

Explanation

**Step-by-Step Solution:**

1. **Understanding Aluminium's Reactivity**: Aluminium is known as a reactive metal, meaning it has the potential to react with various substances, including oxygen and water.

2. **Formation of Aluminium Oxide**: When aluminium is exposed to air, it reacts with oxygen to form aluminium oxide (Al2O3). This reaction occurs quickly and is a natural process for aluminium.

3. **Dull Layer Formation**: The aluminium oxide layer that forms on the surface of aluminium is dull and acts as a protective barrier. This layer adheres strongly to the metal and does not easily come off.

4. **Passive Metal**: Once the aluminium oxide layer is formed, aluminium becomes a passive metal. This means that it does not readily react with further exposure to air or water because the oxide layer prevents additional oxidation.

5. **Conclusion**: Therefore, aluminium does not react readily with air or water because it is covered with a protective layer of aluminium oxide, which inhibits further reactions.

**Final Answer**: Aluminium does not react readily with air or water because it is covered with a layer of aluminium oxide (Al2O3) that prevents further oxidation.

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