Write short notes on CuO + H2 -> Cu + H2O.

Step 1: Write short notes on $\text{CuO} + \text{H}_2 \rightarrow \text{Cu} + \text{H}_2\text{O}$.
This is a reduction reaction. Copper(II) oxide reacts with hydrogen gas to form copper metal and water. In this reaction, copper(II) oxide is reduced to copper (its oxidation state changes from +2 to 0), and hydrogen is oxidized to water (its oxidation state changes from 0 to +1). Hydrogen acts as a reducing agent.

$$\text{CuO}(s) + \text{H}_2(g) \rightarrow \text{Cu}(s) + \text{H}_2\text{O}(l)$$