Question

Ammonia is a Lewis base and it forms complexes with many cations. Which one of the following cations does not form a complex with ammonia?

• A. ${Ag}^{+}$
• B. ${Cu}^{2+}$
• C. ${Cd}^{2+}$
• D. ${Pb}^{2+}$

Answer 1

The correct option is D ${Pb}^{2+}$

Ammonia is a lewis base. It forms complexes with transition elements like $A{g}^{+},C{u}^{2+},C{d}^{2+}$ but it does not form complex with $P{b}^{2+}$ as it is not a transition element.

$AgCl+N{H}_{4}OH⟶\left[Ag{\left(N{H}_3\right)}_2\right]Cl+2H_{2}O$

$CuS{O}_4+4N{H}_{4}OH⟶\left[Cu{\left(N{H}_3\right)}_4\right]S{O}_4+4H_{2}O$

$CdS{O}_4+4N{H}_{4}OH⟶\left[Cd{\left(N{H}_3\right)}_4\right]S{O}_4+4H_{2}O$

Option D is correct.