Oxygen in the air combines with the copper statue to form copper oxide, which is green. which of these is the correct chemical reaction for this? a) cu + o → cuo eliminate b) cu + o2 → cuo c) cuo → cu + o2 d) 2 cu + o2 → 2cuo

D, 2Cu + O2 → 2CuO. A is wrong because oxygen is a diatomic element, meaning it always has to come in the form of O2 in the case of gas. B is wrong because the equation isn't balanced correctly; there's two oxygens on the reactants side, while only one oxygen on the products side. C is wrong because it's saying you're STARTING OUT with CuO already: that doesn't correspond with the word problem. Thus leaves D, where the equation is balanced correctly, has the diatomic oxygen, and ends with CuO.

elements make up everything, and they combine to make compounds.

the answer is c