Answer
[tex]S^{2-}(aq)+Fe^{2+}(aq)\operatorname{\rightarrow}FeS(s)[/tex]Explanation
The reaction is a double displacement reaction.
Step 1: Write the balanced molecular equation with the state of the substances as shown below:
[tex]K_2S(aq)+Fe(NO_3)_2(aq)\rightarrow2KNO_3(aq)+FeS(s)[/tex]Step 2: Split the substances into ions (ionic equations):
[tex]2K^++S^{2-}+Fe^{2+}+2NO_3^-\operatorname{\rightarrow}2K^++2NO_3^-+FeS[/tex]Step 3: Cancel out the spectators on both sides of the complete ionic equation in step 2.
[tex]S^{2-}+Fe^{2+}\operatorname{\rightarrow}FeS[/tex]Step 4: Write the remaining substances as the net ionic equation.
[tex]S^{2-}(aq)+Fe^{2+}(aq)\operatorname{\rightarrow}FeS(s)[/tex]