Final answer:
Option A is the correct answer, as it correctly matches the names and formulas of the chromate and dichromate polyatomic ions. Chromate is CrO42- and dichromate is Cr2O72-.
Step-by-step explanation:
The correct names and formulas for polyatomic ions are as follows: chromate is CrO42-, dichromate is Cr2O72-, nitrite is NO2-, and nitrate is NO3-. Sulfite is SO32-, and sulfate is SO42-. The carbonate ion is CO32-, and the bicarbonate is HCO3-. Therefore, option A which gives the names as chromate: CrO42-; dichromate: Cr2O72- is correct.