Ques. 1JEE Main 2025, 7 April (Evening Shift)
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). In the light of the above statements, choose the most appropriate answer from the options given below:
- Both (A) and (R) are correct and (R) is the correct explanation of (A)
- (A) is correct but (R) is not correct
- (A) is not correct but (R) is correct
- Both (A) and (R) are correct but (R) is not the correct explanation of (A)
Answer
(2) (A) is correct but (R) is not correct
Solution
Assertion: glass (n 1.5) is optically denser than air (n 1.0003), so its refractive index is higher. (A) is correct.
Reason: optical density means the ability of a medium to slow down light (it decides the refractive index); it is not the same as mass density and is not proportional to it. For example, turpentine has a lower mass density than water but a higher refractive index (1.47 > 1.33). (R) is not correct.
Answer: (2)