JEE Main · 2024 · 30 Jan 2024 · Shift 1 · Classification of Elements and Periodicity

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Given below are the two statements: one is labeled as Assertion (A) and the other is labeled as Reason (R).

Assertion (A): There is a considerable increase in covalent radius from N to P. However from As to Bi only a small increase in covalent radius is observed.

Reason (R): covalent and ionic radii in a particular oxidation state increases down the group.

In the light of the above statement, choose the most appropriate answer from the options given below:
  1. (A)(A) is false but (R) is true
  2. (B)Both (A) and (R) are true but (R) is not the correct explanation of (A)✓ Correct
  3. (C)(A) is true but (R) is false
  4. (D)Both (A) and (R) are true and (R) is the correct explanation of (A)

Answer: (B)

Solution

Assertion is factually correct: covalent radius rises sharply from N to P but only slightly from As to Bi.

Reason states the general trend (radius increases down a group), which is true but does not explain the anomaly — the real cause is poor shielding by the filled - and -orbitals of the heavier elements (d-block and lanthanoid contraction).

So both statements are true, but R is not the correct explanation of A.

JEE Main · 2024 · 30 Jan 2024 · Shift 1 · Single correct option

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