Q1. The greenish coating that develops on copper utensils when they are exposed to moist air is due to the formation of _______.
A Copper oxide
B Copper carbonate Correct
C Copper sulphate
D Copper nitrate
Explanation
Copper reacts slowly with moist air containing carbon dioxide and forms a green coating. At school level, this coating is commonly identified as copper carbonate, more precisely a basic copper carbonate patina. Copper oxide is usually black, so it does not match the greenish deposit described here. Copper sulphate is blue in its hydrated form and is not formed simply by exposure of utensils to moist air. Copper nitrate is associated with reaction with nitric acid, not ordinary moist air. Hence the green coating points to copper carbonate.