alleryThe greenish layer that forms on a copper vessel kept in moist air is mainly which compound?
ACopper hydroxide
BCopper sulphide
CCopper chloride
DCopper carbonate
Answer & Solution
Correct answer: D. Copper carbonate
1. Carbon dioxide in moist air reacts with the copper surface.
2. Copper loses its luster as a greenish layer forms.
3. This greenish layer is copper carbonate (CuCO3), the process called patination.
4. Silver forms a sulphide layer, but copper here forms a carbonate, so the sulphide option is wrong.
_Source: Balbharati (Maharashtra Board) Class 10 Science & Technology, Ch 8 "Metallurgy", p.115_
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