Question

Why the item made of silver turn black when exposed to air

Answer 1

Silver is a shinning metal object. It generally do not react with oxygen easily. But air contains some amount of sulphur compounds like hydrogen sulphide . So slowly silver starts combining with hydrogen sulphide present in air. So silver forms black when exposed in air.

Answer 2

Silver objects turn black due to formation of a layer of silver sulphide on their surface. Traces of hydrogen sulphide present in air react with silver to form silver sulphide, which gives metal black appearance.