Answer
Net Ionic: $2Cr^{+3}(aq)$ + $3CO_{2}^{-2}(aq)$ $\rightarrow$ $Cr_{2}(CO_{3})_{3}(s)$
Spectator ions are $NH_{4}^{+}$ and $SO_{4}^{-2}$
Work Step by Step
In the reaction, sulfate and ammonium form a soluble solution so they are they spectator ions since they do not change phase. Chromium and carbonate will react with one another to form a precipitate so they are included in the net ionic since they change phase
