Question

The correct shape and $\mathrm{I}-\mathrm{I}-\mathrm{I}$ bond angles respectively in ${\mathrm{I}}_3^{-}$ ion are:

• A. Trigonal planar; $120°$
• B. Distorted trigonal planar; $135°$and $90°$
• C. Linear; $180°$
• D. T-shaped; $180°$ and $90°$

Answer 1

The correct option is C

Linear; $180°$

The correct option is (C):

Explanation for the correct answer:

${\mathrm{I}}_3^{-}$ shape:

1. Basically there is the presence of 2 bonds as well as 3 lone pairs in ${\mathrm{I}}_3^{-}$
2. As there are three Iodine atoms present in ${\mathrm{I}}_3^{-}$ .
3. Among all the three atoms in ${\mathrm{I}}_3^{-}$, there is the presence of negative charge on one atom which will further give the three lone pairs and the 2 bonds.
4. So as the three lone pairs will repel each other and due to this they will go equatorial and the 2 bonds will get arranged in the axial.
5. And as the two bonds will be there is axial, so they will posses linear molecular geometry.
6. So , because of linear geometry bond angle present here would be equal to $180°$.
7. 

Therefore, the correct option is (C): Linear; $180°$.