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Difficulty: MediumCorrosion of Metals and Prevention Methods

Aluminium resists atmospheric corrosion better than iron because it rapidly forms a tough, non-porous coating of aluminium oxide (Al2O3Al_2O_3) that prevents oxygen and moisture from reaching the underlying metal.

Answer: Answer

Answer

The statement is TRUE. Aluminium forms an adherent, non-porous protective oxide film (Al2O3Al_2O_3) upon exposure to air, which renders the metal passive and prevents further atmospheric corrosion.
The statement is true because aluminium undergoes passivation in atmospheric air, forming an impermeable, self-healing oxide film (Al2O3Al_2O_3) that insulates the underlying metal from environmental oxygen and moisture.

Step-by-Step Solution

1
Analyze the surface reactivity of aluminium exposed to atmospheric air.
Aluminium rapidly reacts with oxygen to form a thin surface layer of aluminium oxide (Al2O3Al_2O_3).
Aluminium has a high affinity for oxygen due to its electropositive nature.
2
Compare the physical properties of aluminium oxide with those of iron rust.
Unlike iron rust (Fe2O3⋅xH2OFe_2O_3 \cdot xH_2O), which is porous, brittle, and flakes off, the Al2O3Al_2O_3 coating is continuous, tough, and impermeable.
The non-porous nature of Al2O3Al_2O_3 prevents further diffusion of oxygen and moisture to the unreacted metal underneath.

Key Concept

Metal Passivation via Protective Oxide Layer
Estimated Time:45s
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Corrosion of Metals and Prevention Methods

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