Question

Which pair will show common ion effect?

• A. $Ba{Cl}_2+Ba{\left({NO}_3\right)}_2$
• B. $NaCl+HCl$
• C. ${NH}_{4}OH+{NH}_{4}Cl$
• D. $AgCN+KCN$

Answer 1

The correct option is C ${NH}_{4}OH+{NH}_{4}Cl$

Those ions will show common ion effect in which one or both them does not dissociate completely.

$NaCl$ and $HCl$ dissociate completely as one of them is acid and other is salt of strong acid and strong base.

$AgCN$ and $KCN$ dissociate completely as one of them is acid and other is salt of strong acid and strong base.

NH4OH is weak base to which NH4Cl is added which provides common $N{H}_4^{+}$ion dissociation of NH4OH is suppressed.