Final answer:
The spectator ions in the given equation are 2NO3- and 2Na+, as they appear unchanged on both sides of the equation and do not participate in the reaction.
Step-by-step explanation:
The spectator ions in a chemical reaction are ions that exist in the same form on both the reactant and product sides of a chemical equation. They do not participate in the actual chemical reaction and can be omitted when writing the net ionic equation. In the provided equation Ba2+ + 2NO3- + 2Na+ + SO42- → BaSO4(s) + 2NO3- + 2Na+, the spectator ions are 2NO3- (d) and 2Na+ since they appear in the same form on both sides of the equation and do not change during the course of the reaction. Therefore, they are not involved in the formation of the precipitate BaSO4 and are present solely to maintain charge neutrality.