How much hydrogen is required to completely reduce copper oxide 2?

Given:
m (CuO) = 20 g

To find:
V (H2) -?

1) Write the reaction equation:
H2 + CuO => Cu + H2O;
2) Calculate the molar mass of CuO:
M (CuO) = Mr (CuO) = Ar (Cu) * N (Cu) + Ar (O) * N (O) = 64 * 1 + 16 * 1 = 80 g / mol;
3) Calculate the amount of CuO substance:
n (CuO) = m (CuO) / M (CuO) = 20/80 = 0.25 mol;
4) Determine the amount of substance H2:
n (H2) = n (CuO) = 0.25 mol;
5) Calculate the volume of H2 (under normal conditions):
V (H2) = n (H2) * Vm = 0.25 * 22.4 = 5.6 liters.

Answer: The volume of H2 is 5.6 liters.