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.
Use of the empirical formula
Answer:
A catalyst increases the rate of reaction by decreasing activation energy. ... Enzymes are highly substrate specific and catalyze reactions by providing an alternate pathway of lower activation energy.
Explanation:
I hope this helps :)
mass * temp change * specific heat
make sure the specific heat value is in Joules