Question

Artificial gem used for cutting glass is:
(A) graphite
(B) diamond
(C) SiC
(D) $CaC{{N}_{2}}$

Answer 1

Hint: SiC is used and known for its hardness. Diamond is also the hardest material known . Graphite is one of the allotropes of carbon. It is much softer than diamond and therefore, used for lubrication purposes and in pencil lead.

Complete Solution :
- Graphite is a crystalline form of the element carbon with its atoms arranged in a hexagonal structure. It occurs naturally in this form and is the most stable form of carbon under standard conditions. It is converted to diamond under high pressures and temperatures. Graphite is used in pencils and lubricants. It is a good conductor of heat and electricity due to the presence of one free electron. Its high conductivity makes it useful in electronic products such as electrodes, batteries, and solar panels.
- Diamond is a solid allotrope of the element carbon with its atoms arranged in a crystal structure called diamond cubic which is having 8 atoms in one lattice. At room temperature and pressure, another allotrope of carbon known as graphite is the chemically stable form of carbon, but diamond almost never converts to it. Diamonds have the highest hardness and thermal conductivity of any natural material, properties of diamond that are utilized in major industrial applications are cutting and polishing tools.
- Silicon carbide (SiC), also known as carborundum, is a semiconductor of silicon and carbon. It occurs in nature as the extremely rare mineral moissanite. In the arts, silicon carbide, due to the durability and low cost of the material, is a popular abrasive in modern lapidary . Silicon carbide is used as a support and shelving material in high temperature kilns such as for firing ceramics, glass fusing, or glass casting. SiC kiln shelves are lighter and considerably more durable than traditional alumina shelves.
- Calcium cyanamide is the inorganic compound with the formula $CaC{{N}_{2}}$. It is the calcium salt of the cyanamide ($C{{N}_{2}}^{2-}$) anion. This is used as chemical fertilizer and is commercially known as nitrolime.
So, the correct answer is “Option C”.

Note: Graphite and graphite powder are in industrial applications because of their self-lubricating and dry lubricating properties. In manufacturing, Silicon carbide is used for its hardness in abrasive machining processes such as grinding, honing, water-jet cutting and sandblasting.