Answer
(a) $Ag_2CO_3$
(b) $PbCO_3$
(c) $AgCN$
Work Step by Step
(a) and (b)
$CO_3^{2-}$ act as a weak base in water, following the reaction:
$CO_3^{2-}(aq) + H_2O(l) \lt -- \gt HCO_3^-(aq) + OH^-(aq)$
Since the carbonate ion is being consumed, its concentration will decrease, increasing the solubility of the salts.
(c)
The same will occur with the $CN^-$ ion, which is also a base.
$CN^-(aq) + H_2O(l) \lt -- \gt HCN(aq) + OH^-(aq)$
