A 1.00 g sample of a hydrogen peroxide (H2O2) solution is placed in an Erlenmeyer flask and diluted — Stoichiometry Chemistry Question

A 1.00 g sample of a hydrogen peroxide (H₂O₂) solution is placed in an Erlenmeyer flask and diluted with 20 mL of 1 M aqueous sulfuric acid. To this solution is added 0.0200 M KMnO₄ solution via a buret, until a pale purple color persists. This requires 22.50 mL of KMnO₄ solution. What is the percent by mass of hydrogen peroxide in the original solution?