Respuesta :
Answer:
because the product of CuO contains 2 molecules so it is unbalanced
Explanation:
to balance it 2Cu+2O=4CuO now it is balanced
Because the two before the cuo means there is 2 moles of each atom and in the reactants there is only one mole of each so to balance the equation u need to put 2 before the cu and before the o