Question

Hydrochloric acid is not used in permanganate titrations.

Answer 1

Acid is needed to provide the H+ (aq) ions, so that this particular reaction occurs. If HCl (aq) were used instead of sulfuric acid, the permanganate ions would oxidise the Cl- ions to form Cl2 (g) and so would not be available to react with the oxalic acid.