Write the net ionic equation (including phases) that corresponds to fe(clo4)2

1) The question is incomplete. What is the compound which Fe(ClO4)2 reacts with?

It could be one of several salts.

2) Assuming it is Na2S the complete reaction is:

Fe(ClO4)2 (aq) + Na2S(aq) → FeS (s) + 2NaClO4 (aq)

So, the next steps how how to work this problem assuming that reaction.

3) Show the ionic compounds as separate ions.

Fe(2+) (aq) + 2 ClO4(-) (aq) + 2 Na(+) (aq) + S(2-) (aq) → FeS(s) + 2 Na(aq) + 2 ClO4(-) (aq)

That is the total ionic equation.

4) Cancel the ions that appear on both sides of the equation , Na(+) and ClO4(-).

Fe(2+) (aq) + S(2-) (aq) → FeS(s)  < this is the net ionic equation

What happens to sodium and perchlorate is that they do not participate in the reaction but remain dissolved which is called "spectator ions".