In which of the following states maximum iron ore is found?
(1) FeCO3
(2) Fe2O3
(3) Fe3O4
(4) FeS2
Answer: (2) Iron ores are rocks and minerals from which metallic iron can be economically extracted. The iron itself is usually found in the form of magnetite (Fe3O4), hematite (Fe2O3), goethite (FeO(OH), limonite (FeO(OH).n(H2O)), or siderite (FeCO3). Hematite, also spelled as haematite, is the mineral form of iron(III) oxide (Fe2O3), one of several iron oxides. It is mined as the main ore of iron. Huge deposits of hematite are found in banded iron formations. Gray hematite is typically found in places where there has been standing water or mineral hot springs, such as those in Yellowstone National Park in the United States.
