AIIMS 2019 Chemistry Molecular Geometry MCQ Question
Assertion : and are not isostructural.
Reason : In , sulphur has one lone pair of electrons.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Correct Answer
Detailed Explanation
Option A is correct because the structure of BO₃³⁻ (borate ion) features a trigonal planar geometry with a central boron atom bonded to three oxygen atoms, each with a formal charge of -1, resulting in an overall charge of -3. In contrast, SO₃²⁻ (sulfite ion) has a tetrahedral arrangement around the sulfur atom, with one of the oxygen atoms bearing a double bond and the other two single-bonded with a -1 charge each, leading to a total charge of -2. The distinct geometries and bonding characteristics of these polyatomic ions highlight the differences in their electron configurations and resonance structures.
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