Assertion : All F - S - F angle in `SF_(4)` are greater than `90^(@)` but less than `180^(@)`.
Reason :The lone pair -bond pair repulsion is weaker than bond pair -bond pair repulsion

Options

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

Explanation

To solve the given assertion and reason question, we need to analyze both statements carefully.

### Step 1: Analyze the Assertion
The assertion states that "All F - S - F angles in SF4 are greater than 90° but less than 180°."

- **Structure of SF4**: Sulfur tetrafluoride (SF4) has a seesaw molecular geometry due to the presence of one lone pair of electrons on the sulfur atom.
- **Bond Angles**: In SF4, the F-S-F bond angles are not uniform. The axial F-S-F bond angles are approximately 180°, while the equatorial F-S-F bond angles are around 102° and 89°.
- **Conclusion for Assertion**: Since not all angles are greater than 90° (specifically, one angle is 89°), the assertion is **false**.

### Step 2: Analyze the Reason
The reason states that "The lone pair-bond pair repulsion is weaker than bond pair-bond pair repulsion."

- **VSEPR Theory**: According to the Valence Shell Electron Pair Repulsion (VSEPR) theory, the repulsion between lone pairs is greater than the repulsion between bond pairs. Therefore, the repulsion between a lone pair and a bond pair is indeed weaker than that between two bond pairs.
- **Conclusion for Reason**: The statement is **false** because the lone pair-bond pair repulsion is stronger than bond pair-bond pair repulsion.

### Final Conclusion
Both the assertion and the reason are false. Therefore, the correct answer is option D: Both assertion and reason are false.

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