Explain the "Reduction" in terms of gain or loss of oxygen with two examples.

(N/A) Reduction is defined as the loss of oxygen from a substance during a chemical reaction.
For example:
$(i)$ $\mathop {CO_2 + H_2 \to CO}\limits_{\text{Removal of oxygen - reduction}} + H_2O$
$(ii)$ $\mathop {CuO + H_2 \xrightarrow{\Delta } Cu}\limits_{\text{Loss of oxygen - reduction}} + H_2O$
In equation $(i)$, $CO_2$ is reduced to $CO$ due to the loss of oxygen, and in equation $(ii)$, $CuO$ is reduced to $Cu$ due to the loss of oxygen.