A student has been collecting silver coins and copper coins. One day she observed a black coating on silver coins and a green coating on copper coins. Which chemical phenomenon is responsible for these coatings? Write the names of black and green coatings.
When a copper object is exposed to moist air for a long time,then a green coating is formed on its surface.
(a) What is the material of the green coating ?
(b) State whether the green coating is acidic or basic.