Question

Which of the following is considered as the hardest mineral?
(A) Iron
(B) Talc
(C) Bauxite
(D) Diamond

Answer 1

Hint: Minerals are the solid substances which are present in our nature. These can be made of one element or more than one element combined together. Gold, Silver and carbon are the elements which are forming the minerals on their own. They are also termed as the native elements.

Complete answer:
Between the room temperature and 912 degrees C, iron is having the BCC structure. Thus it is a tough and hard metal.
According to the scale, Talc is being considered as the softest. It can be scratched by all other materials.
Bauxite is a type of sedimentary rock having relatively high aluminium content. It is considered as the world's main source of aluminium as well as gallium.
Diamonds are at the top of Friedrich Mohs scale of the mineral hardness scale. After it, topaz, quartz, feldspar, apatite, fluorite, calcite and gypsum are in the list. These are incredibly hard as they have crystallized in its particular atomic shape. This shape results from heat and pressure on Earth at a depth of 140 to 150km.
Diamond is found as the solid form of the element carbon. Its atoms are arranged in the crystal structure. This is known as the diamond cubic. At the room temperature and pressure, another such solid form of carbon is popular as graphite. It is a chemically stable form of the carbon, but diamond almost never converts into it. Diamond is valuable due to the diamond's natural strength and unique visual appearance in combination with its relative rarity.

The correct answer is D.

Note:
The outermost shell of each carbon atom is having four electrons. In the diamond, these electrons are shared with the other four carbon atoms. Thus, it is forming very strong chemical bonds resulting in the extremely rigid tetrahedral crystal.