Copper is more reactive than silver. Hence, it displaces silver from the silver nitrate solution according to the given reaction.
Cu(s) + 2AgNO3(aq) --------> Cu(NO3)2(aq) + 2Ag(s)
Copper Silver nitrate Copper(lI) nitrate Silver
The silver thus forrmed is deposited on the surface of copper, thereby giving it a u,hite shining appearance.
The solution becomes blue due to the formation of copper-nitrate