Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Diamond is used for cutting glass.
Reason (R): Diamond has a high refractive index.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Both (A) and (R) are correct but (R) is not the correct explanation of (A)
Assertion (A): Diamond is used for cutting glass. True. Diamond is the hardest natural substance (10 on the Mohs scale); a hard material scratches a softer one, so a diamond tip scores glass for cutting.
Reason (R): Diamond has a high refractive index. True. Its refractive index is about 2.42, one of the highest of any natural material.
R does not explain A. The high refractive index causes total internal reflection inside a cut diamond and makes it sparkle; it has nothing to do with cutting. The cutting comes from its hardness, which in turn comes from the strong network of carbon–carbon bonds in its crystal.