How much copper is required to obtain 8 g of copper oxide (2)?

for this we need to calculate the amount of substance (number of moles) according to the following formula:
n (CuO) = m (CuO) / Mr (CuO),
We need to find the molar mass of copper oxide (2). It is calculated:
Mr (CuO) = Mr (Cu) + Mr (O) = 64 + 16 = 80 g / mol.
Then:
n (CuO) = 8/80 = 0.1 mol
Find the number of moles of copper:
n (Cu) = n (CuO) * Mr (Cu) / Mr (CuO) = 0.1 * 64/80 = 0.1 * 0.8 = 0.08 mol.
Then the mass of copper is calculated using the following formula:
m (Cu) = n (Cu) * Mr (Cu) = 0.08 * 64 = 5.12 g.
Answer: 5.12 grams of copper is needed