Upon complete reduction of 200 g of copper (II) oxide with hydrogen, metallic copper was formed in mass.

1. Let us compose the equation of the reaction proceeding during the reduction of copper oxide with hydrogen:

CuO + H2 = Cu + H2O;

2. Let’s calculate the chemical amount of copper oxide:

n (CuO) = m (CuO): M (CuO);

M (CuO) = 64 + 16 = 80 g / mol;

n (CuO) = 200: 80 = 2.5 mol;

3. Determine the amount of copper:

n (Cu) = n (CuO) = 2.5 mol;

4. Find the mass of copper:

m (Cu) = n (Cu) * M (Cu) = 2.5 * 64 = 160 g.

Answer: 160 BC