Question

When nitric acid $HN{O}_3$ reacts with metals, hydrogen gas is not observed because

• A. Metallic hydrides are formed.
• B. Hydrogen is oxidised by nitric acid.
• C. Metal weakly react with nitric acid.
• D. Hydrogen is reduced by nitric acid.

Answer 1

The correct option is B

Hydrogen is oxidised by nitric acid.

Most of the metals do not react with $HN{O}_3$ because it is a strong oxidizing agent. And since hydrogen is a reducing agent, nitric acid oxidises the hydrogen produced to water and itself undergoes reduction to give $N_{2}O$,$NO$,$N{O}_2$,$N_2$ and $N{H}_3$. Hence, when metals (except Mn and Mg) are treated with nitric acid, hydrogen gas is not liberated.