Final answer:
The spectator ions for the reaction between K₂CO₃ and HBr are K⁺ and Br⁻, as they appear unchanged on both sides of the equation. option d is correct.
Step-by-step explanation:
The spectator ions for the reaction that occurs when aqueous solutions of K₂CO₃ and HBr are mixed are the ions that do not participate in the reaction. When these two solutions react, the products are KBr and H₂CO₃ (carbonic acid, which typically decomposes into CO₂ and H₂O).
The spectator ions are the ones that appear unchanged on both sides of the equation. The K⁺ (potassium) and Br⁻ (bromide) ions do not undergo a chemical change during the reaction and are present in the same form in the reactants and the products, therefore, the correct answer is d. K⁺ and Br⁻.