Question

Cooper doesn't burn but hot metal is coated with a black coloured layer of copper oxide

Answer 1

The thinlayer of copper oxide is a protective cover which protects copper from further oxidation. Thus this copper oxide does not burn as it is already reacted with the oxygen in the air.

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Answer 2

It's for protect it from oxidation and corrosion.



And makes it to seems like new one forever .



And avoid Rusting .


These are some features for why it is coated with black colour.