Question

Question 7
Generally, metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals, except $\text{Mn}$ and $\text{Mg}$?

(a) ${\text{H}}_2{\text{SO}}_4$
(b) $\text{HCl}$
(c) ${\text{HNO}}_3$
(d) All of these

Answer 1

Option (c) is correct.

Hydrogen gas is not evolved when a metal reacts with nitric acid. It is because ${\text{HNO}}_3$ is a strong oxidizing agent. It oxidizes the ${\text{H}}_2$ to water and itself gets reduced to any of the nitrogen oxides ${\text{N}}_2\text{O},\text{NO},{\text{NO}}_2$. But magnesium $\left(\text{Mg}\right)$ and manganese $\left(\text{Mn}\right)$ react with very dilute ${\text{HNO}}_3$ to evolve ${\text{H}}_2$ gas.