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JEE Main 2025 Apr 4 Shift 2, Chemistry Q19: Valence Shell Electron Pair Repulsion (VSEPR) Theory

JEE Main2025Apr 4, Shift 2Chemistry
Q.

Given below are two statements:

Statement (I) : for , all three possible structures may be drawn as follows.

Statement (II) : Structure III is most stable, as the orbitals having the lone pairs are axial, where the repulsion is minimum.

In the light of the above statements, choose the most appropriate answer from the options given below:

  1. A

    Statement I is incorrect but statement II is correct.

  2. B

    Statement I is correct but statement II is incorrect.

  3. C

    Both Statement I and statement II are correct.

  4. D

    Both Statement I and statement II are incorrect.

Solution

Statement (I) is correct: with hybridisation, three drawings can be sketched on paper showing the two lone pairs in different combinations of axial/equatorial sites.

Statement (II) is incorrect in two ways. First, it misdescribes structure III, where the lone pairs are actually equatorial, not axial. Second, in a trigonal bipyramidal geometry the lone pairs always prefer the equatorial positions, because equatorial sites have only two near-90° neighbours whereas axial sites have three.
The observed T-shape of is the result of both lone pairs occupying equatorial positions; this minimises lp-bp repulsion.

Statement I correct, Statement II incorrect.

Concept behind this question

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