Question

Hydrogen can be prepared by the action of dilute $H_{2}S{O}_4$ on:

• A. copper
• B. iron
• C. lead
• D. mercury

Answer 1

Answer: (B)

iron

$A)$ Copper does not react with dilute sulphuric acid as its reduction potential is higher than that of hydrogen. Copper does not displace hydrogen from non-oxidizing acids like $HCl$ or dilute $H_{2}S{O}_4$. But, concentrated sulphuric acid is an oxidizing agent.

$B)$ Hydrogen gas is evolved when dilute hydrochloric acid is added to a reactive metal. When iron reacts with dilute $H_{2}S{O}_4$, Iron $\left(II\right)$ sulphate with the evolution of hydrogen gas is formed. Hydrogen gas is produced when dilute hydrochloric acid is added to a reactive metal.

$C)$ The surface of metallic lead is protected by a thin layer of lead oxide $PbO$. This renders the lead essentially insoluble in sulfuric acid.

$D)$ Mercury does not react with non-oxidizing acids but does react with concentrated nitric acid, $HN{O}_3$, or concentrated sulphuric acid, $H_{2}S{O}_4$, to form mercury$\left(II\right)$ compounds together with nitrogen or sulphur oxides.

$Hencethecorrectanswerisoption\left(B\right)$