Assertion : In trigonal bipyramidal structure two axial bonds are longer than the equatorial bonds.
Reason : Axial bonds suffer more repulsion as compared to equatorial bonds.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

To solve the question regarding the assertion and reason about the trigonal bipyramidal structure, we will analyze both statements step by step.

### Step 1: Understand the Assertion
The assertion states that in a trigonal bipyramidal structure, the two axial bonds are longer than the equatorial bonds.

**Explanation**: In a trigonal bipyramidal geometry, there are five bonds arranged with three in the equatorial plane and two in the axial positions. Due to the spatial arrangement, the axial bonds experience different interactions compared to the equatorial bonds.

### Step 2: Understand the Reason
The reason provided states that axial bonds suffer more repulsion compared to equatorial bonds.

**Explanation**: In a trigonal bipyramidal structure, the axial bonds are oriented vertically while the equatorial bonds are arranged horizontally. The axial bonds are subjected to greater electron-electron repulsion because they are positioned 90 degrees to the equatorial bonds, leading to increased repulsion. This repulsion causes the axial bonds to be longer than the equatorial bonds.

### Step 3: Analyze the Example of PCl5
To support the assertion and reason, we can examine the molecular structure of phosphorus pentachloride (PCl5).

1. **Hybridization**: The hybridization of phosphorus in PCl5 is sp³d, which corresponds to a trigonal bipyramidal structure.
2. **Bond Angles**: In this structure, the bond angles between equatorial bonds are 120 degrees, while the bond angles between axial and equatorial bonds are 90 degrees.
3. **Repulsion**: The axial bonds experience more repulsion due to their orientation, leading to a lengthening of these bonds compared to the equatorial bonds.

### Conclusion
Both the assertion and the reason are correct. The reason provided correctly explains why the axial bonds are longer than the equatorial bonds due to the increased repulsion experienced by the axial bonds.

### Final Answer
Both assertion and reason are correct, and the reason is the correct explanation for the assertion.

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