Question

silver does not combine easily with oxygen but silver jewellery tarnishes after sometime. why?

Answer 1

It is sulphur and not oxygen that tarnishes silver in the atmosphere. Silver is a transitional metal. This means that it less reactive and it does not readily react with oxygen. However, silver reacts with sulphur quite easily and it is this reaction with sulphur compounds in the atmosphere that tarnishes silver. The compound formed that causes the tarnish is Ag2S