Ram was gifted a metallic ring by his father on his birthday. After a few weeks, he observed that his ring was turning black from the outer surface and hence he consulted his science teacher. What explanation Ram might have been given by his teacher?
1
The ring must be of iron and started rusting.
2
It was a silver ring and started turning black due to the sulphur compounds such as hydrogen sulphide (H2S) present in the air.
3
The black coating over the copper ring is the result of the corrosion of copper.
4
The ring must be an alloy of lead and tin and turned black due to reaction with oxygen.