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Answer: (a) 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 chemical phenomenon which is responsible for this is known as corrosion, in which a metal is attacked by substances around it such as moisture, acids, etc., and gets corroded. Due to this corrosion, the color of Silver changes to black, on its surface.

Metals such as silver when attacked by substances around it such as moisture, acids, gases etc, are said to corrode and this phenomenon is called corrosion. The black substance is formed because silver (Ag) reacts with H2S present in air. It forms thin black coating of silver sulphide (Ag2S).

Therefore, the black substance formed is Silver sulfide and it's chemical formula is Ag 2 S .

The silver article becomes black after sometimes when exposed to air because silver reacts with sulphur which is present in the atmosphere and then forms silver sulphide. Thus the layer of this silver sulphide is formed on the surface of the silver article so they appear as dull or black.

Silver articles, when exposed to air become black after sometime. This is because the silver metal reacts with sulphur present in the atmosphere and forms silver sulphide. Thus, a layer of silver sulphide is formed on the surface of silver articles, because of which they appear dull and black.

Due to the reaction of silver with the oxygen present in the atmosphere Silver oxide turns black in colour. After an interval of time, it will form silver sulphide after coming in contact with oxygen and Hydrogen sulphide present in the atmospheric air. The phenomenon is known as corrosion.