When iodine is dissolved in aqueous potassium iodide, the shape of the species formed is :

Options

A. linear
B. angular
C. triangular
D. see-saw

Answer

To determine the shape of the species formed when iodine is dissolved in aqueous potassium iodide, we follow these steps:

### Step-by-Step Solution:

1. **Identify the Reaction**: When iodine (I2) is dissolved in aqueous potassium iodide (KI), it forms the tri-iodide ion (I3^-). The reaction can be represented as:
\[ I_2 + KI \rightarrow KI_3 \]
Here, the tri-iodide ion is the key species we need to analyze.

2. **Determine the Composition of I3^-**: The tri-iodide ion (I3^-) consists of three iodine atoms. In this ion, one iodine atom is bonded to two other iodine atoms, and there is an overall negative charge.

3. **Count Valence Electrons**: Iodine is in group 17 of the periodic table and has 7 valence electrons. For the tri-iodide ion:
- Total valence electrons from three iodine atoms = \(3 \times 7 = 21\)
- Since the ion has a -1 charge, we add one more electron: \(21 + 1 = 22\) valence electrons.

4. **Draw the Lewis Structure**: In the Lewis structure of I3^-, one iodine atom will be the central atom, and the other two iodine atoms will be bonded to it. The structure can be represented as:
\[ I - I - I \]
The central iodine atom will have two bonding pairs and three lone pairs of electrons.

5. **Determine Hybridization**: The hybridization can be determined by counting the regions of electron density around the central iodine atom. In this case:
- There are 2 bonding pairs (from the two I-I bonds) and 3 lone pairs.
- Total regions of electron density = 2 (bonding) + 3 (lone pairs) = 5.
- This corresponds to \(sp^3d\) hybridization.

6. **Determine the Shape**: The geometry of a molecule with \(sp^3d\) hybridization and 2 bonding pairs and 3 lone pairs is linear. The lone pairs will occupy equatorial positions in a trigonal bipyramidal arrangement, leaving the bonding pairs in a linear arrangement.

7. **Conclusion**: Therefore, the shape of the tri-iodide ion (I3^-) formed when iodine is dissolved in aqueous potassium iodide is linear.

### Final Answer:
The shape of the species formed (I3^-) is linear.

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