givereason:

1.lemon is used for restoring the shine of tarnished copper vessels.

2.a metal sulphide is converted into its oxide to extract metal from it.

 

1. Lemon contains citric acid. Tamarind contains tartaric acid. This acid neutralises the copper carbonate and dissolves the layer. The copper carbonate is formed as a result of its exposure t the moist carbon dioxide present in the air.

 

2. It is because the metals can be extracted easily when converted into its oxide.