Question:

Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Refractive index of glass is more than air.
Reason (R): Optical density of a medium is directly related to its mass density.
In the light of the above statements, choose the correct answer from the options given below.

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When dealing with assertion and reason questions, make sure to verify the truth of each statement and whether the reason correctly explains the assertion.

Updated On: July 22, 2025

(A) is false but (R) is true
(A) is true but (R) is false
Both (A) and (R) are true but (R) is NOT the correct explanation of (A)
Both (A) and (R) are true and (R) is the correct explanation of (A)

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The Correct Option is B

Solution and Explanation

- Assertion (A): The refractive index of a material is the ratio of the speed of light in vacuum to the speed of light in the material. Since the speed of light in glass is slower than that in air, the refractive index of glass is indeed more than that of air. Hence, assertion (A) is true.
- Reason (R): The optical density of a medium is not directly related to its mass density. The refractive index (which determines optical density) is related to the speed of light in the material, while mass density relates to the mass per unit volume of the material. Therefore, reason (R) is false. Since (A) is true and (R) is false, the correct answer is (2) "Assertion (A) is true but (R) is false."

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