Explain the following giving reasons
`[NiCI_(4)]^(2-)` is tetrahedral and paramagnetic whereas `[Ni(CN)_(4)]^(2-)` is square plannar and dimagnetic.

Explanation

To explain why \([NiCl_4]^{2-}\) is tetrahedral and paramagnetic while \([Ni(CN)_4]^{2-}\) is square planar and diamagnetic, we need to analyze the nature of the ligands, the electronic configuration of nickel, and the resulting hybridization and geometry of the complexes.

### Step 1: Determine the oxidation state of Nickel in both complexes
- In both complexes, Nickel is in the +2 oxidation state.

### Step 2: Write the electronic configuration of Ni²⁺
- Nickel (Ni) has an atomic number of 28. The ground state electronic configuration is \([Ar] 3d^8 4s^2\).
- For Ni²⁺, we remove two electrons from the 4s orbital, resulting in the configuration:
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