`I_(2)` has less solubility in water and its solubility increase on adding KI solution. When KI and `I_(2)` react then a species 'X' is formed by which solubility of `I_(2)` increases.
Which of the following of the is the correct characteristic of anionic part of 'X' ?
[Polar and non-polar nature to be considered on the basis of dipole moment]
(I) Planar (II) non-planar (III) polar (IV) non-polar

Options

A. I and II
B. I and IV
C. II and III
D. II and IV

Explanation

To solve the question, we need to determine the characteristics of the anionic part of the species 'X' formed when potassium iodide (KI) reacts with iodine (I₂). The species 'X' is identified as \( I_3^- \) (triiodide ion). Let's break down the solution step by step:

### Step 1: Identify the Reaction
When KI is added to a solution of I₂, the following reaction occurs:
\[ I_2 + KI \rightarrow KI_3 \]
In this reaction, the triiodide ion \( I_3^- \) is formed, which is the anionic part we need to analyze.

### Step 2: Determine the Structure of \( I_3^- \)
The \( I_3^- \) ion can be represented as:
\[ I_3^- = I - I - I \]
Here, one iodine atom is the central atom, and the other two iodine atoms are bonded to it.

### Step 3: Calculate the Hybridization
To find the hybridization of the central iodine atom in \( I_3^- \):
- The central iodine has 7 valence electrons.
- The negative charge indicates that it has gained an additional electron, giving it 8 valence electrons.
- The central iodine forms bonds with 2 other iodine atoms and has 3 lone pairs of electrons.

The steric number (the number of bonded atoms plus lone pairs) is:
\[ \text{Steric Number} = 2 \text{ (bond pairs)} + 3 \text{ (lone pairs)} = 5 \]
For a steric number of 5, the hybridization is \( sp^3d \).

### Step 4: Determine the Geometry
The geometry corresponding to \( sp^3d \) hybridization is trigonal bipyramidal. In this geometry, the lone pairs will occupy the equatorial positions to minimize repulsion, while the bonded iodine atoms will occupy the axial positions.

### Step 5: Analyze the Planarity and Polarity
1. **Planarity**: The arrangement of the three iodine atoms in \( I_3^- \) is linear, which is a planar structure.
2. **Polarity**: The dipole moments of the bonds in \( I_3^- \) will cancel each other out because the three iodine atoms are arranged in a straight line. Therefore, the overall dipole moment is zero, indicating that \( I_3^- \) is non-polar.

### Conclusion
Based on the analysis, the characteristics of the anionic part \( I_3^- \) are:
- It is planar (due to its linear structure).
- It is non-polar (due to the cancellation of dipole moments).

Thus, the correct characteristics of the anionic part of 'X' are:
- (I) Planar
- (IV) Non-polar

The answer is option B: (I) and (IV).