WAEC Chemistry 2023 Paper

Concept:Dilute trioxonitrate(V) acid does not release hydrogen gas because it acts as a strong oxidizing agent, not as a typical acid.Explanation:Trioxonitrate(V) acid is $\mathrm{HNO}_3$, commonly called nitric acid.It is a powerful oxidizing agent.When it reacts with metals, it oxidizes any hydrogen that might be formed.The hydrogen atoms are converted into water instead of escaping as hydrogen gas, $\mathrm{H_2}$.The acid itself is reduced during the reaction.For example, with copper: $3\mathrm{Cu} + 8\mathrm{HNO}_3 \rightarrow 3\mathrm{Cu(NO_3)_2} + 2\mathrm{NO} + 4\mathrm{H_2O}$.This shows that the oxidizing property of the acid prevents hydrogen production.Therefore, the reason is not corrosion or absence of reaction, but the strong oxidizing nature of the acid.Answer:D. it is a strong oxidizing agent.