The correct shape and $\mathrm{I}-\mathrm{I}-\mathrm{I}$ bond angles respectively in $\mathrm{I}_{3}^{-}$ion are:

(B) T- shaped ; $180^{\circ}$ and $90^{\circ}$

(C) Trigonal planar; $120^{\circ}$

(D) Distorted trigonal planar; $135^{\circ}$ and $90^{\circ}$

JEE Main · 2021 · 24 Feb 2021 · Shift 2 · Chemical Bonding and Molecular Structure

The correct shape and

I - I - I

bond angles respectively in

I_{3}^{-}

ion are:

(A)Linear; $18 0^{\circ}$ ✓ Correct
(B)T- shaped ; $18 0^{\circ}$ and $9 0^{\circ}$
(C)Trigonal planar; $12 0^{\circ}$
(D)Distorted trigonal planar; $13 5^{\circ}$ and $9 0^{\circ}$

Answer: (A)

Solution

The triiodide ion is formed when an iodide ion donates a lone pair into a molecule of iodine, so the central atom ends up with two bond pairs and three lone pairs, a steric number of five, and a trigonal bipyramidal arrangement of electron pairs. Lone pairs repel more strongly than bond pairs and so take the three equatorial positions, where they are

12 0^{\circ}

apart, leaving the two bonded atoms in the axial positions directly opposite each other. The ion is therefore linear, with a bond angle of

18 0^{\circ}

JEE Main · 2021 · 24 Feb 2021 · Shift 2 · Single correct option

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JEE Main · 2021 · 24 Feb 2021 · Shift 2 · Chemical Bonding and Molecular Structure

Solution

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