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Question
What is tarnishing? Give an example.
Solution
Tarnishing of metal articles:
Shiny metal surfaces and other articles lose their shining appearance due to chemical reactions on the surface. For example, silver articles become black on exposure to atmospheric air.
Similarly, brass vessels which contain copper as one of the constituents develop a greenish layer on exposure to air for a long time. This is due to a chemical reaction between copper and moist air to form basic copper carbonate and copper hydroxide.
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