Question

Copper becomes green when exposed to moist air for a long period. This is due to:

• A. the formation of a layer of cupric oxide on the surface of copper.
• B. the formation of a layer of basic carbonate of copper on the surface of copper.
• C. the formation of a layer of cupric hydroxide on the surface of copper.
• D. the formation of basic copper sulphate layer on the surface of the metal.

Answer 1

Answer: (B)

the formation of a layer of basic carbonate of copper on the surface of copper.

Answer 2

Copper when exposed to moist air having $CO_2$. It gets superficially coated with a green layer of basic carbonate $CuCO_3. Cu (OH)_2$.