Solubility products of , , and are , , and , respectively. The cation that will precipitate first as — Ionic Equilibrium Chemistry Question

Question

Solubility products of $\text{Mg(OH)}_2$, $\text{Cd(OH)}_2$, $\text{Al(OH)}_3$ and $\text{Zn(OH)}_2$ are $4 \times 10^{-11}$, $8 \times 10^{-6}$, $8.5 \times 10^{-23}$ and $1.8 \times 10^{-14}$, respectively. The cation that will precipitate first as hydroxide, on adding limited quantity of $\text{NH}_4\text{OH}$ in a solution containing equimolar amount of metal cations, is