Question

Assertion:
Carborundum is used as an abrasive.
Reason:
Its structure is similar to that of diamond.
A. Both assertion and reason are correct and reason is the correct explanation for assertion.
B. Both assertion and reason are correct but reason is not the correct explanation for assertion.
C. Assertion is correct but reason is incorrect
D. Both assertion and reason are incorrect.

Answer 1

We need to understand what carborundum is, its uses, and its similarities to the structure of diamonds. Carborundum is also known as silicon carbide and has the molecular formula $SiC$. It is a semiconductor having composition of carbon and silicon. It has a crystal-like structure. It is a man-made inorganic crystal formed by the carbothermal reduction of silica. Although it is extremely rare in nature but can be found in the mineral moissanite.

Complete step by step answer:
Abrasives are substances used to smooth out materials through extensive rubbing in order to rid of the unwanted roughness or substances on the surface. One example is the use of sandpaper in polishing furniture.
Let us evaluate the assertion statement:
Carborundum is ultra-hard in nature, just like diamonds and has a similar crystalline structure. Its constituent particles are held together by a network of covalent bonds throughout the crystal. It is therefore used as an abrasive due to its hardness and low cost as compared to diamonds.
Let us evaluate the reason statement:
The structure of carborundum is similar to that of a diamond but the reason it is used as an abrasive is due to its low cost.
Hence, both the reason and assertion statements are correct but the reason is not the correct explanation for assertion.

So, the correct answer is Option B.

Note: It must be noted that the only compound of silicon and carbon carborundum. The carbon atom is attached to silicon through a triple bond. The appearance is yellow to green to bluish-black. $SiC$does occur naturally rarely as the mineral moissanite. However, it has been mass-produced in powder form for use as an abrasive since $1893$.