(a) Name an alloy of copper. State its chemical composition and any one use.(b) Explain why, when a copper object remains in damp air for a considerable time, a green coating is formed on its surface. What is this process known as ?

(a) An alloy of copper is brass. Brass contains Copper (Cu) – 80% and Zinc (Zn) – 20%. It is used for making utensils.

(b) Copper reacts slowly with the carbon dioxide and water to form a green coating of basic copper carbonate on the surface of the object. The formation of this green coating of basic copper carbonate corrodes and the process is called corrosion of copper.