Question

Select the correct Chemical formula of corundum from the given options.
A. $A{{l}_{2}}{{O}_{3}}.2{{H}_{2}}O$
B. $SiC$
C. $A{{l}_{2}}{{O}_{3}}.{{H}_{2}}O$
D. $A{{l}_{2}}{{O}_{3}}$

Answer 1

Hint: There are approximately 117 elements found in the earth. Few of them such as noble gases occur free in nature, while others occur in combined form with other elements forming compounds. If in these compounds an element is present in extensive quantity then the compound is termed as ore. Corundum is itself an ore of one element which is used in making utensils.

Complete step-by-step answer:Ores are the naturally occurring minerals from which a metal can be extracted through metallurgical processes. Corundum is also an ore. It is the ore of Aluminum and therefore aluminum is found in abundance in corundum.
Chemically, corundum exists as a crystalline form of aluminum oxide. Its chemical formula is$\left( A{{l}_{2}}{{O}_{3}} \right)$. It is generally a rock-forming mineral. Aluminum is found in a large proportion in corundum. It also contains traces of iron, chromium, vanadium and titanium.
Corundum generally has two gem varieties. These are sapphire and ruby. Rubies are rich in chromium and thus are red in color whereas sapphire exists in various colors depending on the specific transition metal present in it.
We should remember that Corundum is widely known for its rigid nature and extreme hardness. The extensive hardness makes the mineral an excellent abrasive and when this hardness is carved into specific intricate sizes, then they form beautiful gemstones. These gemstones are used as rings in fingers by people across the globe as a sign of good fortune and noble astrology.
We should note that corundum is primarily found in the metamorphic and igneous rocks such as syenite, pegmatite etc.
Looking at the other options $A{{l}_{2}}{{O}_{3}}.2{{H}_{2}}O$ is the chemical formula of Bauxite. $SiC$ is the chemical formula of carborundum. $A{{l}_{2}}{{O}_{3}}$is the chemical formula of Boehmite.

Hence, the correct option is D.

Note: It should be noted that synthetic as well as natural corundum because of their toughness and rigidity are used in a wide variety of different industrial applications. They are extensively used in the manufacturing of industrial bearings, electronic instruments etc.