Which of the following would have a permanent dipole moment ?

Options

A. `BF_(3)`
B. `SiF_(4)`
C. `SF_(4)`
D. `XeF_(4)`

Answer

To determine which of the given compounds has a permanent dipole moment, we need to analyze the molecular structures and hybridizations of each compound. Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Compounds and Their Hybridizations
1. **Identify the compounds**: The compounds in question are BF3, SiF4, SF4, and XeF4.
2. **Determine hybridizations**:
- BF3: sp2 hybridized
- SiF4: sp3 hybridized
- SF4: sp3d hybridized
- XeF4: sp3d2 hybridized

### Step 2: Analyze the Molecular Geometry and Dipole Moments
1. **BF3**:
- Geometry: Trigonal planar.
- Dipole moment: The dipole moments of the B-F bonds cancel each other out due to symmetry, resulting in a net dipole moment of zero.

2. **SiF4**:
- Geometry: Tetrahedral.
- Dipole moment: Similar to BF3, the dipole moments of the Si-F bonds cancel each other out due to symmetry, resulting in a net dipole moment of zero.

3. **SF4**:
- Geometry: Trigonal bipyramidal with one lone pair.
- Dipole moment: The presence of a lone pair distorts the shape, leading to an unequal distribution of dipole moments. The dipole moments do not cancel out, resulting in a permanent dipole moment.

4. **XeF4**:
- Geometry: Square planar with two lone pairs.
- Dipole moment: The dipole moments of the Xe-F bonds cancel each other out due to symmetry, resulting in a net dipole moment of zero.

### Step 3: Conclusion
Based on the analysis, the only compound that exhibits a permanent dipole moment is **SF4**.

### Final Answer:
The compound with a permanent dipole moment is **SF4**.

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