Identify the substances that are oxidised and that are reduced in the following equation.
(i) 4Na(s) + O2(g) → 2Na2O(s)
(ii) CuO(s) + H2(g) → Cu(s) + H2O(l)
With the addition of oxygen (O2) in the first equation, the sodium (Na) becomes oxidised, and the reduction of copper (Cu) in the second equation results from the addition of hydrogen (H2).