What is the name of FeSO4?

The compound FeSO₄ is named Iron(II) sulfate because the iron in this compound is in the +2 oxidation state. When naming ionic compounds, it is important to indicate the oxidation state of the metal cation, especially when the metal can exhibit multiple oxidation states.

Iron can exist in both +2 and +3 states. In this case, the sulfate ion (SO₄²⁻) has a -2 charge. Therefore, to balance this charge, iron must be in the +2 state, making it Iron(II) sulfate. The Roman numeral II signifies this +2 oxidation state.

The other choices represent different compounds or incorrect oxidation states, where Iron(III) sulfate would indicate +3 charge, Iron oxide is a different class of compounds entirely, and Iron phosphate focuses on a different anionic group. Thus, naming FeSO₄ as Iron(II) sulfate accurately reflects the charge of the iron ion in the compound.