The strength of an aqueous NaOH solution is most accurately determined by titrating:
(Note: consider that an appropriate indicator is used)
Reaction of an inorganic sulphite X with dilute $\mathrm{H}_2 \mathrm{SO}_4$ generates compound Y.Reaction of Y with NaOH gives X. Further, the reaction of X with Y and water affords compound Z. Y and Z, respectively, are :
If you spill a chemical toilet cleaning liquid on your hand, your first aid would be :