You have to find the reaction involving sodium iodide and ozone or O₃. If you search in the internet, the reaction would be
O₃<span>(g) + 2 NaI(aq) + H</span>₂O(l) → O₂<span>(g) + I</span>₂<span>(g) + 2 NaOH(aq) </span> Using the stoichiometric coefficients in the reaction, the solution would be