Answer
$PbI_2$ isn't more soluble in acidic solution than in pure water, because there are no significant bases in the ionic compound.
Work Step by Step
1. Identify the acidity/basicity of each ion in the compound:
- $Pb^{2+}$: No significant acidity/basicity;
- $I^{-}$: No significant acidity/basicity. (It is the conjugate pair of a Strong acid ($HI$))
- Since we don't have any significant acid/base, the acidity of the solution will not affect the solubility of the compound.
