Question

The metal which cannot liberate $H_2$ gas from hydrochloric acid is:

• A. Zn
• B. Cu
• C. Mg
• D. Al

Answer 1

The correct option is B Cu

Cu is higher up in the electrochemical series than $H^{+}$
Hence copper cannot reduce $H^{+}to{H}_2$
$asSRPofCu>SRPof{H}^{+}$
and $E_{cell}=SRPof{H}^{+}-SRPofC{u}^{2+}<0$
as $E_{cell}<0$
$\therefore$ The reaction cannot take place.

Hence, option B is correct.