Corrosion is an electrochemical process. Iron corrodes to form hydrated iron oxides, which are commonly called rust. Unlike aluminium and zinc, which form protective oxide layers (passivation), rust does not adhere strongly to the surface and is permeable to air and water, allowing corrosion to continue unchecked. Silver tarnishes by reacting with sulfur, forming a thin layer of silver sulfide, but this is a surface phenomenon and not as destructive as the rusting of iron.
Which one of the following elements corrodes rapidly?
Asked in UPSC NDA 1 2017 · Topic: Metals, Minerals, Ores: Properties, Uses (Corrosion of metals: causes, mechanism (rusting), and prevention methods (galvanization, anodizing, electroplating, alloying, painting))
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