Question

answer me fast plz.........
A student has been collecting silver coins and and Copper Coins. One day he observed a
black coating on Silver Coins and green Coating on Copper Coins. Give the Chemical Name
of black and green Coating. How are they formed.

Answer 1

the black coating is known as silver sulphide which is formed when they react with hydrogen sulphide.
the green coating is known as basic copper carbonate formed when carbon dioxide comes in contact with copper.
hope it helps

Answer 2

silver and copper are oxidised in presence of oxygen