Final answer:
The correct chemical reaction for preparing sodium chromate by oxidizing sodium peroxide is 2 Na2O2 + CrO3 → 2 Na2CrO4, reflecting the proper stoichiometry and conservation of mass with chromium remaining in the +6 oxidation state.
Step-by-step explanation:
To determine the correct reaction for the preparation of sodium chromate by oxidizing sodium peroxide, it is important to know the chemical formula of sodium chromate which is Na2CrO4. The correct reaction must reflect the proper stoichiometry and conservation of mass. Based on the reactions presented, the correct option is b) 2 Na2O2 + CrO3 → 2 Na2CrO4. This equation shows the oxidation of sodium peroxide (Na2O2) with chromium(VI) oxide (CrO3) to yield sodium chromate (Na2CrO4).
Additionally, the oxidation state of chromium in chromium(VI) oxide is +6, the same as in sodium chromate, indicating that there's no change in the oxidation state of chromium in this reaction. It matches the known oxidation chemistry where CrO3 transforms into the chromate ion CrO42-.