Silver articles becomes black on prolonged exposure to air. This is due to the formation of (a) Ag2O (b) Ag2S (c) AgCN (d) Ag2O and Ag2S
Option (b) Ag2S: Silver is a highly unreactive metal and thus it does not react with oxygen easily. But, when this Silver is exposed to the air for a very long time, it then reacts with Hydrogen sulfide gas that is present in the air. Thus this reaction, results in the formation of Silver sulfide which makes the silver article makes black.
