In which of the following molecules are all the bonds not equal ?

Options

A. `AlF_3`
B. `NF_3`
C. `ClF_3`
D. `BF_3`

Explanation

To determine which of the given molecules has unequal bonds, we will analyze the molecular geometry and hybridization of each molecule provided.

### Step-by-Step Solution:

1. **Identify the Molecules**: The question presents four molecules: AlF3, NF3, ClF3, and BF3. We need to analyze each of these to determine the equality of their bonds.

2. **Analyze AlF3**:
- **Hybridization**: AlF3 has an aluminum atom bonded to three fluorine atoms.
- **Geometry**: The molecular geometry is trigonal planar.
- **Bond Equality**: All Al-F bonds are equivalent due to the symmetrical arrangement.
- **Conclusion**: All bonds in AlF3 are equal.

3. **Analyze NF3**:
- **Hybridization**: NF3 has a nitrogen atom bonded to three fluorine atoms.
- **Geometry**: The molecular geometry is trigonal pyramidal (similar to NH3).
- **Bond Equality**: All N-F bonds are equivalent due to the symmetrical arrangement around the nitrogen atom.
- **Conclusion**: All bonds in NF3 are equal.

4. **Analyze ClF3**:
- **Hybridization**: ClF3 has a chlorine atom bonded to three fluorine atoms with two lone pairs.
- **Geometry**: The molecular geometry is T-shaped due to the presence of lone pairs.
- **Bond Equality**: The axial Cl-F bonds are longer than the equatorial Cl-F bond due to lone pair-lone pair repulsion, leading to unequal bond lengths.
- **Conclusion**: Not all bonds in ClF3 are equal.

5. **Analyze BF3**:
- **Hybridization**: BF3 has a boron atom bonded to three fluorine atoms.
- **Geometry**: The molecular geometry is trigonal planar.
- **Bond Equality**: All B-F bonds are equivalent due to the symmetrical arrangement.
- **Conclusion**: All bonds in BF3 are equal.

### Final Answer:
Among the given molecules, **ClF3** is the only molecule where not all the bonds are equal.