Correct Answer: sulphur

Solution : The correct answer is sulphur .

Silver articles become black after their exposure to air because they react with the sulphur present in the air. It forms a layer of silver sulphide on the surface. Because of this formation of the silver sulphide layer, the silver appears black and dull. It is a highly unreactive metal. But with prolonged exposure to sulphur of Hydrogen Sulphide, it loses its shine.

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