Question

why do siover article turn black and copper items turn green after some time​

Answer 1

Silver article turns black when kept in the air because silver article reacts with sulphur compounds such as hydrogen sulphide (H2S) present in air. The phenomenon is called corrosion. For silver particularly, it is called tarnishing of silver.

Copper turns green because of chemical reactions with the elements. Just as iron that is left unprotected in open air will corrode and form a flaky orange-red outer layer, copper that is exposed to the elements undergoes a series of chemical reactions that give the shiny metal a pale green outer layer called a patina.

hope it helps

Answer 2

Silver artikle become black on exposure to air for sometime .they exposed to air silver react with sulpher present in atmosphere and form a black layer .silver sulphide

Copperreact with water and air .

Layer mainly contain black cuoand greencu(oh)2