Identify the incorrect statement related to `PCl_5` from th following:

Options

A. Two axial P-Cl bonds make an angle of `180^@` with each other
B. Axial P-Cl bonds are longer than equatorial P-Cl bonds
C. `PCl_5` molecule is non-reactive
D. Three equatorial P-Cl bonds make an angle of `120^@` with each other

Answer

To identify the incorrect statement related to \( PCl_5 \), we can follow these steps:

### Step 1: Understand the Structure of \( PCl_5 \)
- Phosphorus pentachloride (\( PCl_5 \)) has a trigonal bipyramidal structure.
- In this structure, there are three equatorial chlorines and two axial chlorines.

### Step 2: Analyze the Bond Angles
- The bond angles for the equatorial chlorines are \( 120^\circ \) with each other.
- The bond angles for the axial chlorines are \( 180^\circ \) relative to each other.

### Step 3: Evaluate the Length of the Bonds
- The axial \( P-Cl \) bonds are longer than the equatorial \( P-Cl \) bonds due to the repulsion between the axial and equatorial bonds.

### Step 4: Assess Reactivity
- \( PCl_5 \) is known to be reactive, particularly with water, where it can hydrolyze to form \( POCl_3 \) and \( HCl \).
- Therefore, any statement claiming that \( PCl_5 \) is non-reactive is incorrect.

### Step 5: Review the Statements
- Based on the analysis:
1. The angles between the equatorial bonds are \( 120^\circ \) - **Correct**
2. The axial \( P-Cl \) bonds are longer than the equatorial \( P-Cl \) bonds - **Correct**
3. \( PCl_5 \) is non-reactive - **Incorrect**
4. The angle between the axial \( P-Cl \) bonds is \( 180^\circ \) - **Correct**

### Conclusion
The incorrect statement related to \( PCl_5 \) is that it is non-reactive. Thus, the answer is option 3.

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