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Aluminium is more reactive than iron. Bu...

Aluminium is more reactive than iron. But aluminium is less easily corroded than iron because.

A

Iron forms mono and divalent ions.

B

Iron undergoes reaction easily with water

C

Oxygen forms a protective oxide layer on aluminium.

D

Aliminium is a noble metal.

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The correct Answer is:
To understand why aluminium is more reactive than iron but less easily corroded, we can break down the explanation into several steps: ### Step 1: Understanding Reactivity - **Reactivity** refers to how readily a substance undergoes a chemical reaction. In this case, aluminium is more reactive than iron, meaning it can react more readily with other substances. ### Step 2: Corrosion Definition - **Corrosion** is the process where metals deteriorate due to reactions with environmental factors, such as moisture and oxygen. ### Step 3: Aluminium and Iron in Corrosion - Although aluminium is more reactive, it is less prone to corrosion compared to iron. This is an important distinction. ### Step 4: Formation of Oxide Layers - When aluminium is exposed to air, it reacts with oxygen to form a thin layer of aluminium oxide (Al2O3). This layer is very stable and adheres strongly to the surface of the aluminium. ### Step 5: Protective Properties of Aluminium Oxide - The aluminium oxide layer acts as a **protective barrier** that prevents further oxidation of the underlying aluminium. This phenomenon is known as **protective passivation**. ### Step 6: Comparison with Iron - In contrast, iron does not form a protective oxide layer. Instead, when iron oxidizes, it forms rust (iron oxide), which is flaky and does not adhere well to the surface. This allows moisture and oxygen to continue to react with the underlying iron, leading to more corrosion. ### Conclusion - Therefore, the reason aluminium is less easily corroded than iron, despite being more reactive, is due to the formation of a protective oxide layer (Al2O3) that prevents further reactions. ### Final Answer - The correct option is: **Oxygen forms a protective oxide layer on aluminium.** ---
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