Why does copper powder turn black when heated in air?
Answer and explanation
Correct answer: Due to formation of black copper(II) oxide (CuO)
When copper powder is heated in air, it combines with oxygen and forms black copper(II) oxide: 2Cu + O₂ → 2CuO. The black CuO coating changes the appearance of the copper powder. Copper(I) oxide, Cu₂O, is red, copper carbonate is not formed under these conditions, and ordinary heating in air does not mean that copper melts; therefore option A is unambiguous.
Frequently asked questions
What is the correct answer to this question?
Due to formation of black copper(II) oxide (CuO)
Why is this the correct answer?
When copper powder is heated in air, it combines with oxygen and forms black copper(II) oxide: 2Cu + O₂ → 2CuO. The black CuO coating changes the appearance of the copper powder. Copper(I) oxide, Cu₂O, is red, copper carbonate is not formed under these conditions, and ordinary heating in air does not mean that copper melts; therefore option A is unambiguous.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Chemical Reactions and Equations.
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