This is how I look at these kinds of problems in which it is given if its in aqueous, solid, liquid, or gaseous forms.
I look at the ones that are in aqueous form. Every compound/ion that is in aqueous form is the spectator ion.
This may not be the correct way to deal with these types of problems but it seems easy to me. I may be wrong. Please anyone feel free to correct me. There are a lot of knowledgeable people using this forum that will hopefully provide a better explanation about this.
Thx Ibraiz. How do you make sure ALL compound/ions that are in aqueous form could be the spectator ion??
As we know, a spectator ion is not changed in both sides (reactant/product) so that it can be omitted from the reaction equation.