Question:
Electrical wires made of aluminum
Electrical wires made of aluminum
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Think about the thin oxide film that forms on aluminium in air.
Updated On: Nov 3, 2026
- corrode easily as aluminium is a very reactive metal.
- corrode easily because porous flaky aluminium oxide is formed.
- do not corrode easily as aluminium oxide forms a protective layer.
- do not corrode easily as aluminium is less reactive than metals like sodium, magnesium and zinc.
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The Correct Option is C
Solution and Explanation
Step 1: Recall what happens to aluminium in air:
Aluminium is a fairly reactive metal. When it is exposed to air, it quickly reacts with oxygen and forms a very thin layer of aluminium oxide:
\[ 4\mathrm{Al} + 3\mathrm{O_2} \to 2\mathrm{Al_2O_3} \]
This oxide layer is hard, thin and non-porous. It sticks firmly to the metal surface.
Step 2: Link it to wires:
The oxide layer blocks air and moisture from reaching the metal below. So the corrosion stops after the first thin layer forms.
This is why aluminium wires last long and do not corrode easily. This is option C.
Step 3: Why the other options are wrong:
Option A is wrong. Aluminium is reactive, but that is the reason the protective oxide forms. It does not lead to easy corrosion.
Option B is wrong. The oxide of aluminium is not porous or flaky. A flaky, porous layer is typical of rust on iron, which lets corrosion go deeper.
Option D is wrong. Aluminium is more reactive than zinc, not less. Also, reactivity is not the reason for resisting corrosion. The oxide layer is.
Final Answer:
Aluminium wires do not corrode easily because a protective oxide layer forms on them. This is option C. \[ \boxed{\text{C}} \]
Aluminium is a fairly reactive metal. When it is exposed to air, it quickly reacts with oxygen and forms a very thin layer of aluminium oxide:
\[ 4\mathrm{Al} + 3\mathrm{O_2} \to 2\mathrm{Al_2O_3} \]
This oxide layer is hard, thin and non-porous. It sticks firmly to the metal surface.
Step 2: Link it to wires:
The oxide layer blocks air and moisture from reaching the metal below. So the corrosion stops after the first thin layer forms.
This is why aluminium wires last long and do not corrode easily. This is option C.
Step 3: Why the other options are wrong:
Option A is wrong. Aluminium is reactive, but that is the reason the protective oxide forms. It does not lead to easy corrosion.
Option B is wrong. The oxide of aluminium is not porous or flaky. A flaky, porous layer is typical of rust on iron, which lets corrosion go deeper.
Option D is wrong. Aluminium is more reactive than zinc, not less. Also, reactivity is not the reason for resisting corrosion. The oxide layer is.
Final Answer:
Aluminium wires do not corrode easily because a protective oxide layer forms on them. This is option C. \[ \boxed{\text{C}} \]
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