Question

Aastha has been collecting silver and copper coins if you observed a black and green coating on them and write the chemical name of the black and green coatings which chemical phenomena is responsible for these coatings

Answer 1

the chemical phenomena is responsible of the coating is the property of corrosion of metals the silver and copper coins Erode natures so there is a black and green coating for that reason they have galvanized the metals to prevent corrosion

Answer 2

black coating on silver is due to formation of silver sulphide and green coating on copper is due to the formation of copper carbonate.
the chemical phenomena responsible for it is corrosion