Final answer:
The binary ionic compound for Chromium(II) oxide is CrO.
Step-by-step explanation:
The binary ionic compound for Chromium(II) oxide is option A: CrO.
Chromium has multiple oxidation states, and to determine the correct formula, we need to balance the charges of the ions involved. In this case, Chromium(II) has a +2 charge, while Oxygen has a -2 charge. To balance the charges, we need one Chromium(II) ion and one Oxygen ion, giving us the formula CrO.