Shiny brown copper powder turns black when heated in air. This is because the copper has been

reduced to pure copperCorrect answerYour answercovered with soot from the flameCorrect answerYour answermeltedCorrect answerYour answeroxidised to copper oxideCorrect answerYour answer

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CorrectNot quiteAnswer D

Correct answer: D

2Cu + O₂ → 2CuO; copper gains oxygen.
Gain of oxygen is oxidation, and copper oxide is black.

Worth noting

Passing hydrogen over the hot black powder turns it brown again: that reverse step is reduction.

Concept: Oxidation
Typical timeTypical: 60 s
Your timeYours: —

The rule this testsChemical reactions

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Shiny brown copper powder turns black when heated in air. This is because the copper has been

Explanation