Question

Carbonate ore is -----?
(A) carnallite
(B) limonite
(C) siderite
(D) horn silver

Answer 1

As we know, that elements are basic units of all types of matter in this universe. Then, how these elements occur in the earth’s crust, atmosphere and the sea. Since, $80\%$ of the elements are known as metals but these are not in pure form. Several impurities are present in these metals.

Complete step by step solution
Elements are found to occur in nature either in free form called native state or in the combined state (in the form of their compounds).

Majority of the metals occurring in the crust of earth in the combined state is in the form of compounds called minerals.

In other words, we can also define mineral as-
The chemical substances which are present in form of which the metal occurs in the earth along with impurities are called minerals. But every mineral is not suitable for the extraction because it may contain either low concentration of metal or may contain impurities which may be difficult to remove or the process of extraction (obtaining pure metal) from that mineral may not be chemically feasible.

Thus, the mineral from which the metal is conveniently and economically extracted is called ore.
- The siderite is represented as ${\rm{FeC}}{{\rm{O}}_{\rm{3}}}$ and hence it is a carbonate ore.
- Carnallite contains magnesium. It is ${\rm{KCl}}{\rm{.MgC}}{{\rm{l}}_{\rm{2}}}{\rm{.6}}{{\rm{H}}_{\rm{2}}}{\rm{O}}$
- Limonite is a hydrated iron or is an iron ore and represented as ${\rm{2F}}{{\rm{e}}_2}{{\rm{O}}_3}{\rm{.3}}{{\rm{H}}_{\rm{2}}}{\rm{O}}$.
- Horn silver is a silver ore and represented as ${\rm{AgCl}}$
**Therefore, the correct option is option (C).

Note: **
All ores are mineral but all minerals are not ores.Ores are only those minerals from which metal can be extracted feasibly.