Final answer:
Hematite is best described as an ore containing iron oxide, a compound of iron and oxygen in a fixed ratio, with ionic bonds holding the atoms together. It is not an alloy or a pure metal but a naturally occurring mineral formed of iron oxide molecules.
Step-by-step explanation:
The phrase that best describes hematite is C. an ore containing iron oxide.
Hematite, a mineral form of iron(III) oxide (Fe₂O₃), is an example of an ore from which iron can be extracted. Iron oxide is a compound containing 2 elements, iron (Fe) and oxygen (O), in a fixed ratio. Hematite is not a pure metal, a metal alloy, or a mixture of metals; instead, it is a naturally occurring mineral that contains iron in the form of iron oxide.
Regarding the composition of iron oxide, it is made of metal atoms from iron and nonmetal atoms from oxygen. The relative proportion of atoms in Fe₂O₃ means there are two iron atoms for every three oxygen atoms. The iron and oxygen atoms are bound together by ionic bonds, which occur due to the electrostatic attraction between the positively charged iron ions and the negatively charged oxygen ions.
Iron oxide is not a homogeneous mixture like an alloy (which is a mixture of metals, one of which is a metal by definition). Instead, each particle of iron oxide is a molecule, not an individual atom, because it consists of more than one atom bonded together. Unlike alloys, such as steel, which is made by adding other elements to iron like carbon to modify its properties, hematite is mined directly from the earth in its oxide form.