Which formula/name pair is incorrect? A) FeSO4 iron(II) sulfate B) Fe2 (SO3)3 iron(III) sulfite C) FeS iron(II) sulfide D) FeSO3 iron(II) sulfite E) Fe2 (SO4)3 iron(III) sulfide

The correct answer is E.

Explanation

• Fe2(SO4)3 contains sulfate ions $SO_4^{2-}$. Three sulfates give $3\times(-2)=-6$, so two iron atoms must provide $+6$ total, i.e. $Fe^{3+}$. Therefore Fe2(SO4)3 is iron(III) sulfate, not iron(III) sulfide.
• Iron(III) sulfide (with $S^{2-}$) would have formula Fe2S3.
• The other pairs are correct: FeSO4 = iron(II) sulfate, Fe2(SO3)3 = iron(III) sulfite, FeS = iron(II) sulfide, FeSO3 = iron(II) sulfite.