Final answer:
The correct name for the compound FeS is iron(II) sulfide, indicating that the iron has a +2 oxidation state.
Step-by-step explanation:
The correct name for the compound FeS is iron(II) sulfide. This is because iron can have more than one possible charge, and the charge needs to be included in the name of the compound when this is the case. In FeS, each iron atom has a charge of +2 and combines with a sulfide ion, which has a charge of -2, to form a neutral compound. Therefore, the oxidation state of iron in FeS is +2, and according to the stock system of nomenclature, the name includes the charge of the iron cation in Roman numerals. Hence, the full name of FeS is iron(II) sulfide.