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

$2Cu+{{O}_{2}}\to 2CuO$