Question Detail
Question
The percentage by mass of oxygen in KMnO₄ is: (K=39, Mn=55, O=16)
Correct Answer
Option A is the correct answer.
Detailed Explanation
Molar mass KMnO₄ = 39 + 55 + (4×16) = 158 g/mol. Mass of O = 64 g. %O = (64/158) × 100 = 40.5%.
Hint
Calculate the total molar mass and the mass contribution of oxygen.