When Ag is exposed to air it gets a black coating of
(a)AgNO (b)Ag₂S
(c)Ag₂O (d)Ag₂CO₃
"

Correct Answer: (b) Ag2S

Explanation: When Ag is exposed to air it gets a black coating because silver reacts with H₂S gas present in the air to form a black coating of Ag₂S. The reaction is given below:

$Ag (s) + H_2S (g) → Ag_2S (s) + H_2 (g)$