Question

When metal Z is added to dilute HCl solution, there is no evolution of gas. Metal 'Z' is:

• A. potassium
• B. sodium
• C. silver
• D. zinc

Answer 1

The correct option is C silver

Metals such as sodium, potassium and zinc are more reactive than hydrogen. Hence, they displace it from dilute acids and release hydrogen gas. The reactions involved are as follows:

$2\text{K(s)}+2\text{HCl (aq)}\to 2\text{KCl (aq)}+{\text{H}}_2\text{(g)}2\text{Na(s)}+2\text{HCl (aq)}\to \text{NaCl}\text{(aq)}+{\text{H}}_2\text{(g)}\text{Zn(s)}+2\text{HCl (aq)}\to {\text{ZnCl}}_2\text{(aq)}+{\text{H}}_2\text{(g)}$
On the other hand, silver (Ag) being less reactive than hydrogen fails to displace it from dilute acids. Hence, hydrogen gas is not evolved.

$\text{Ag (s)}+\text{HCl (aq)}\to \text{No reaction}$