Final answer:
The name 'calcium(II) oxide' is incorrect; the correct name is calcium oxide with the formula CaO. Correct formulas for other compounds are Ca(NO3)2 for calcium nitrate, CaCl2 for calcium chloride, and Al2O3 for aluminum oxide.
Step-by-step explanation:
The name 'calcium(II) oxide' is incorrect because calcium forms only one cation with a 2+ charge and is simply called calcium oxide. This ionic compound has the chemical formula CaO, where calcium (Ca) carries a 2+ charge, and oxide (O) carries a 2- charge, resulting in a neutral compound.
For ionic compounds with polyatomic ions, such as calcium nitrate, the correct formula is Ca(NO3)2 due to the charge balance between the calcium ion (Ca2+) and two nitrate ions (NO3-). The correct ionic formula for calcium chloride is CaCl2 and for aluminum oxide is Al2O3 because of the charge balance between the ions involved.