Answers

2015-07-12T18:10:43+05:30
The metal X is copper and black colour coating is formed on it when it is heated in air and the coating is of copper oxide it can  supported by following experiment
1)heat a china dish containing 1g of copper powder or granules.
2)after sometime you will observe a black coating on it due to the oxidation of copper

Cu + O2---on heating---> CuO
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