Question

Generally, pure 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 $Mn$ and $Mg$)?

• A. $H_{2}S{O}_4$
• B. $HCl$
• C. $HN{O}_3$
• D. All of the above

Answer 1

Answer: (C)

$HN{O}_3$

Some of the metals react with dilute acid, forming metal salt and hydrogen, while a few do not react with dilute acids.
Hydrogen gas is not evolved when a metal reacts with nitric acid. It is because $HN{O}_3$ is a strong oxidising agent. It oxidises the $H_2$ produced to water and itself gets reduced to any of the nitrogen oxides ($N_{2}O$, $NO$, $N{O}_2$).