Question

The copper burned in the presence of another substance to form the dark coating on the wire what was that other reactant?

A. Water
B. Oxygen gas
C. Copper oxide
D. Carbon
(The answer is not C I already tried this on the test.)

Answer 1

dark coating is CuO so the reaction must be 2Cu + O2 -> 2CuO

so the other reactant is Oxygen. B

Answer 2

the ans is B, Oxygen gas