Based on the Ksp values and salt analysis cation identification, we can say that order of Ksp value is:
$\mathrm{HgS}<\mathrm{PbS}<\mathrm{AgBr}<\mathrm{Ca}(\mathrm{OH})_{2}$
Ksp values
$\mathrm{HgS} \rightarrow 4 \times 10^{-53}$
$\mathrm{PbS} \rightarrow 8 \times 10^{-28}$
$\mathrm{AgBr} \rightarrow 5 \times 10^{-13}$
$\mathrm{Ca}(\mathrm{OH})_{2} \rightarrow 5.5 \times 10^{-6}$