Question

Explain why surface of some metals acquire a dull appearance when exposed to air for a long time...​

Answer 1

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The surface of some metals acquires a dull appearance when exposed to air for a long time due to:-

the formation of a thin layer of oxide, carbonate or sulphide on their surface by the slow action of the various gases present in air.

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Answer 2

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⚫ Surface o some metals acquires a dull appearance because they react with air or water in the environment to form undesirable compounds (such as Oxides)..This process is called Corrosion.

⚫For example:- Silver tarnishes, Copper develops a green coating, iron loses it's lustre. The corrosion of iron is called Rusting.

⚫The Chemical formula of Rust is = Fe2O3

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