Answer:
CO₃²⁻ + Ca²⁺ → CaCO₃(s)
Explanation:
In a net ionic equation there are listed just the ions that are involved in the reaction.
For the reaction:
Na₂CO₃(aq) + Ca(NO₃)₂(aq) → 2NaNO₃(aq) + CaCO₃(s)
Ions are:
2 Na⁺ + CO₃²⁻ + Ca²⁺ + 2 NO₃⁻ → 2 Na⁺ + 2 NO₃⁻ + CaCO₃(s)
Thus, ions that react are just CO₃²⁻ and Ca²⁺ and net ionic equation is:
CO₃²⁻ + Ca²⁺ → CaCO₃(s)