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On exposure to moist air, copper gains a green coat on its surface due to formation of which one of the following compounds ?

Options

  1. ACopper carbonate
  2. BCopper oxide
  3. CCopper sulphate
  4. DCopper nitrate

Correct answer

A. Copper carbonate

Step-by-step solution

Copper metal when exposed to air turns green in colour due to corrosion. When copper vessel is exposed to air in rainy season, the metal reacts with gases and moisture and atmospheric gases to form a mixture of copper carbonate and copper hydroxide. This gives a green colour to the surface of copper metal. The reaction is as follows: 2 Cu + H ₂ O + CO ₂+ O ₂ Cu ( OH )₂+ CuCO ₃

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