`{:("Column-I","Column-II"),((A)[Ni(CO)_4],(p)"Octahedral paramagnetic"),((B)[Ni(CN)_4]^(-2),(q)"Square planar diamagnetic "),((C)[Ni(NH_3)_6]^(+2),(r)"Tetrahedral diamagnetic "),((D )[NiCl_4]^(-2), (s)"Tetrahedral paramagnetic"):}`

Explanation

To solve the matching question regarding the geometries and magnetic properties of the nickel complexes, we will analyze each complex in Column I and determine its corresponding match in Column II.

### Step-by-Step Solution:

1. **Complex A: [Ni(CO)₄]**
- **Oxidation State**: Nickel in this complex is in the zero oxidation state (Ni^0).
- **Electronic Configuration**: Ni has the configuration [Ar] 3d^8 4s^2.
- **Ligand Field**: CO is a strong field ligand, which causes pairing of electrons.
- **Hybridization**: The hybridization is sp³, leading to a tetrahedral geometry.
- **Magnetic Behavior**: Since all electrons are paired, [Ni(CO)₄] is diamagnetic.
- **Match**: A → (r) "Tetrahedral diamagnetic".

2. **Complex B: [Ni(CN)₄]²⁻**
- **Oxidation State**: Nickel is in the +2 oxidation state (Ni²⁺).
- **Electronic Configuration**: After losing 2 electrons, the configuration is [Ar] 3d^8.
- **Ligand Field**: CN⁻ is also a strong field ligand, leading to pairing of electrons.
- **Hybridization**: The hybridization is dsp², resulting in a square planar geometry.
- **Magnetic Behavior**: All electrons are paired, making [Ni(CN)₄]²⁻ diamagnetic.
- **Match**: B → (q) "Square planar diamagnetic".

3. **Complex C: [Ni(NH₃)₆]²⁺**
- **Oxidation State**: Nickel is in the +2 oxidation state (Ni²⁺).
- **Electronic Configuration**: The configuration remains [Ar] 3d^8 after losing 2 electrons.
- **Ligand Field**: NH₃ is a weak field ligand, which does not cause pairing.
- **Hybridization**: The hybridization is sp³d², leading to an octahedral geometry.
- **Magnetic Behavior**: There are unpaired electrons, making [Ni(NH₃)₆]²⁺ paramagnetic.
- **Match**: C → (p) "Octahedral paramagnetic".

4. **Complex D: [NiCl₄]²⁻**
- **Oxidation State**: Nickel is in the +2 oxidation state (Ni²⁺).
- **Electronic Configuration**: The configuration is [Ar] 3d^8 after losing 2 electrons.
- **Ligand Field**: Cl⁻ is a weak field ligand, which does not cause pairing.
- **Hybridization**: The hybridization is sp³, resulting in a tetrahedral geometry.
- **Magnetic Behavior**: There are unpaired electrons, making [NiCl₄]²⁻ paramagnetic.
- **Match**: D → (s) "Tetrahedral paramagnetic".

### Final Matches:
- A → (r) "Tetrahedral diamagnetic"
- B → (q) "Square planar diamagnetic"
- C → (p) "Octahedral paramagnetic"
- D → (s) "Tetrahedral paramagnetic"