The maximum quantity of lead fluoride which dissolves in $1 \;L$ of water at $20^oC$ is $1.9 \cdot 10^{-3}\;mol$ .
The .......... of $PbF_2$ (not to be confused with the solubility product!!) is equal to $1.9 \cdot 10^{-3}\frac{mol}{L}$
The dissolution is immediately followed by a dissociation to ions.
$PbF_2(s)$ 
$Pb^{2+}(aq)$ $+$ $2F^{-}(aq)$
$1\;L$ of a .......... solution of $PbF_2$ in equilibrium with solid $PbF_2$ contains therefore .......... mol $Pb^{2+}$ and .......... mol $F^-$.
The solubility product at $20^oC$ of $[PbF_2]$ is therefore equal to $K_s$ $=$ $[Pb^{2+}][F^-]^2$ = .......... $\frac{mol^3}{L^3}$
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