Only 2 mL of KMnO4 solution of unknown molarity is required to reach the end point of a titration of 20 mL of oxalic acid (2M) in acidic medium. The molarity of KMnO4 solution should be M.
Answer
8
Solution
Acidic medium: MnO4- Mn2+ (n-factor 5); H2C2O4 2CO2 (n-factor 2)
∵ at the end point, equivalents of KMnO4 = equivalents of oxalic acid
⇒ M 5 2 = 2 2 20
∴ M = 8010 = 8 M
Answer: 8
Note: The official NTA answer key gives 50. Our faculty team has re-checked this question and finds 8 correct, as explained above.