`PCl_(5)` molecule has the following geometry :

Options

A. Trigonal bipyramidal
B. Octahedral
C. Square planar
D. Planar triangular.

Answer

To determine the geometry of the \( PCl_5 \) molecule, we will follow these steps:

### Step 1: Determine the Valence Electrons
Phosphorus (P) is the central atom in \( PCl_5 \). It has 5 valence electrons. Each chlorine (Cl) atom has 7 valence electrons, and there are 5 chlorine atoms.

**Calculation:**
- Valence electrons from phosphorus: 5
- Valence electrons from chlorine: \( 5 \times 7 = 35 \)

Total valence electrons = \( 5 + 35 = 40 \)

### Step 2: Draw the Lewis Structure
In the Lewis structure of \( PCl_5 \), phosphorus forms single bonds with each of the 5 chlorine atoms. There are no lone pairs on the phosphorus atom.

**Lewis Structure:**
- P is at the center with 5 Cl atoms surrounding it, each connected by a single bond.

### Step 3: Calculate the Steric Number
The steric number is calculated as the number of sigma bonds plus the number of lone pairs on the central atom.

**Calculation:**
- Number of sigma bonds = 5 (one for each P-Cl bond)
- Number of lone pairs on phosphorus = 0

Steric number = \( 5 + 0 = 5 \)

### Step 4: Determine the Hybridization
The hybridization can be determined from the steric number. A steric number of 5 corresponds to \( sp^3d \) hybridization.

### Step 5: Predict the Geometry
With \( sp^3d \) hybridization and a steric number of 5, the geometry of the \( PCl_5 \) molecule is trigonal bipyramidal.

### Step 6: Identify the Shape
The shape of the molecule is also trigonal bipyramidal, as there are no lone pairs that would alter the geometry.

### Conclusion
The geometry of the \( PCl_5 \) molecule is **trigonal bipyramidal**.