`Ni(CO)_(4)` is

Options

A. tetrahedral and parmagnetic
B. square planar and diamagnetic
C. tetrahedral and diamagnetic
D. square planar and paramegnetic

Explanation

To determine the properties of nickel carbonyl, \( Ni(CO)_4 \), we can follow these steps:

### Step 1: Determine the electronic configuration of nickel.
Nickel (Ni) has an atomic number of 28. Therefore, its electronic configuration is:
\[ Ni: [Ar] 3d^8 4s^2 \]

### Step 2: Analyze the ligand strength of carbon monoxide (CO).
Carbon monoxide (CO) is a strong field ligand. Strong field ligands have the ability to cause pairing of electrons in the d-orbitals of the metal center.

### Step 3: Consider the effect of CO on the electronic configuration of Ni.
In the presence of CO, which is a strong field ligand, the electrons in the 3d orbitals will pair up. The new configuration will be:
\[ 3d^{10} 4s^0 \]
This means that all the d-electrons are paired, resulting in a diamagnetic complex.

### Step 4: Determine the hybridization of \( Ni(CO)_4 \).
Since \( Ni(CO)_4 \) has four CO ligands, we can determine the hybridization. The central nickel atom will undergo hybridization to accommodate these four ligands. The hybridization can be determined as follows:
- The presence of four ligands suggests \( sp^3 \) hybridization.
- \( sp^3 \) hybridization corresponds to a tetrahedral geometry.

### Step 5: Summarize the properties of \( Ni(CO)_4 \).
- **Magnetism**: Diamagnetic (due to all paired electrons).
- **Hybridization**: \( sp^3 \).
- **Geometry**: Tetrahedral.

### Conclusion:
The correct description of \( Ni(CO)_4 \) is that it is tetrahedral and diamagnetic.