Answer
The spectator ions are: $K^+$ and $NO_3^-$.
Work Step by Step
The ions that do not change after the reaction are called spectator ions.
In this case, the reaction is:
$2K^+(aq) + S^{2-}(aq) + Pb^{2+}(aq) + 2NO_3^-(aq) --\gt$
$PbS(s)+ 2K^+(aq) + 2NO_3(aq)$
The ions that appear on the reactants and products are: $K^+$ and $NO_3$. Therefore, these are the spectator ions.
