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Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Steel is used in the construction of buildings and bridges. Reason (R) : Steel is more elastic and its elastic limit is high. In the light of the above statements, choose the most appropriate answer from the options given below.

Asked in JEE Main 24th Jan 2nd Shift 2023 · Concept and assertion

• (1) Both (A) and (R) are correct but (R) is NOT the correct explanation of (A).
• (2) Both (A) and (R) are correct and (R) is the correct explanation of (A).
• (3) (A) is not correct but (R) is correct.
• (4) (A) is correct but (R) is not correct.

Step-by-step solution

Why the other options are wrong

• (1) comes from accepts both statements but cuts the link between them; the large Y and the high elastic limit are the very reasons an engineer specifies steel, so (R) does explain (A).
• (3) comes from rejects (A), yet steel girders and steel-reinforced concrete are the standard structural members precisely because of the property named in (R).
• (4) comes from rejects (R), usually from the everyday habit of calling rubber 'more elastic' than steel; in physics the more elastic material is the one with the larger modulus, and steel's Y≈2×10¹¹ N m⁻² dwarfs rubber's.

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