QuestionVolumetric analysis / indicators
In which of the following titrations, an external indicator is NOT necessary?
- (a) Titration of oxalate solution with KMnO₄ solution
- (b) Titration of HCl with NaOH solution
- (c) Titration of Hard water with EDTA
- (d) Titration of Na₂CO₃ with HCl solution
Answer: (a) Titration of oxalate solution with KMnO₄ solution
Oxalate–KMnO₄: KMnO₄ acts as its own indicator (pink at end point) → no added indicator needed → (a). HCl–NaOH and Na₂CO₃–HCl need acid-base indicators; EDTA–hard water needs Eriochrome Black T.