Class 12 Maths Chapter 1: Relations and Functions Assertion-reason questions with answers
2 assertion-reason questions on Relations and Functions, each with its answer and the reason, written from the NCERT chapter. For the CBSE board and JEE Main, which are set from the same NCERT chapter. Open a question's solution to check your working; then take the free test to find your next chapter. Each question gives an Assertion (A) and a Reason (R); choose how they stand to each other.
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Answer: (b) Both A and R are true, but R is not the correct explanation of A.
In {1, 2, 3}, R1 with classes {1, 2}, {3} and R2 with classes {1}, {2, 3} are equivalence relations, but R1 ∪ R2 contains (1, 2) and (2, 3) and not (1, 3), so it is not transitive: A is true. R is true (each property holds in both relations, hence in the intersection), but it is about the intersection and does not explain why the union fails.
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Answer: (a) Both A and R are true, and R is the correct explanation of A.
R is the general fact for finite sets, and A is R with X = {1, 2, 3, 4}: four distinct images inside a set of four elements must be all of it. So R explains A.