`[NiCI_(2){P(C_(2)H_(5))_(2)(C_(6)H_(5))}_(2)]` exhibits temperature dependent magnetic behaviour(paramagnetic//diamagnetic) The coordination geometries of `Ni^(2+)` in the paramagnetic and diamagnetic states are respectively .

Options

A. Tetrahedral and tetrahedral
B. Square planar and square planar
C. Tetrahedral and square planar
D. Square planar and tetrahedral

Explanation

To solve the question regarding the coordination geometries of Ni²⁺ in its paramagnetic and diamagnetic states, we can follow these steps:

### Step 1: Determine the Electronic Configuration of Ni²⁺
- Nickel (Ni) has an atomic number of 28. Its electronic configuration is:
\[ \text{Ni: } [Ar] 3d^8 4s^2 \]
- For Ni²⁺, we remove two electrons from the outermost shell (4s), resulting in:
\[ \text{Ni}^{2+}: [Ar] 3d^8 \]

**Hint:** Remember that the removal of electrons for transition metals occurs from the outermost shell first (4s before 3d).

### Step 2: Analyze the Magnetic Properties
- The question states that the compound exhibits temperature-dependent magnetic behavior, which indicates that it can exist in both paramagnetic and diamagnetic states.
- Paramagnetic means there are unpaired electrons, while diamagnetic means all electrons are paired.

### Step 3: Identify the Low Spin and High Spin Complexes
- In a low spin complex (diamagnetic), all electrons are paired. For Ni²⁺ with a d⁸ configuration, this occurs in the presence of strong field ligands, leading to:
- **Hybridization:** \(d^2sp^3\) (using one d, one s, and two p orbitals)
- **Geometry:** Square planar

- In a high spin complex (paramagnetic), some electrons remain unpaired. This occurs in the presence of weak field ligands, leading to:
- **Hybridization:** \(sp^3\) (using one s and three p orbitals)
- **Geometry:** Tetrahedral

### Step 4: Summarize the Findings
- For the paramagnetic state (high spin), the coordination geometry is **tetrahedral**.
- For the diamagnetic state (low spin), the coordination geometry is **square planar**.

### Final Answer
The coordination geometries of Ni²⁺ in the paramagnetic and diamagnetic states are respectively:
- **Paramagnetic:** Tetrahedral
- **Diamagnetic:** Square planar

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