(b)
$AgCl \rightleftharpoons {Ag}^{+} + {Cl}^{-}$
$K_{sp} = \left\lbrack {Ag}^{+} \right\rbrack\left\lbrack {Cl}^{-} \right\rbrack$
$K_{sp} = S^{2}$ ($S$=solubility in mol/L)
$S = \frac{1.435 \times 10^{- 3}\ \frac{g}{L}\ }{143.5} = 1 \times 10^{- 10}$ mol/L