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

Options

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

Explanation

To determine which of the given molecules has bonds that are not equal, we will analyze the molecular structures and hybridizations of each option: ClF3, BF3, AlF3, and NF3.

### Step-by-Step Solution:

1. **Analyze ClF3 (Chlorine Trifluoride)**:
- Chlorine (Cl) is the central atom.
- It has 3 fluorine (F) atoms bonded to it and 2 lone pairs of electrons.
- The molecular geometry is trigonal bipyramidal due to the presence of lone pairs.
- The two lone pairs occupy the equatorial positions, while the fluorine atoms occupy the axial and equatorial positions.
- The bond lengths between Cl and the axial F atoms are different from the bond length to the equatorial F atom due to the lone pair repulsion.
- **Conclusion**: The bonds in ClF3 are not equal.

2. **Analyze BF3 (Boron Trifluoride)**:
- Boron (B) is the central atom.
- It has 3 fluorine atoms bonded to it and no lone pairs.
- The molecular geometry is trigonal planar.
- All bond lengths between B and F are equal due to the symmetrical arrangement.
- **Conclusion**: The bonds in BF3 are equal.

3. **Analyze AlF3 (Aluminum Trifluoride)**:
- Aluminum (Al) is the central atom.
- It has 3 fluorine atoms bonded to it and no lone pairs.
- The molecular geometry is also trigonal planar.
- All bond lengths between Al and F are equal due to the symmetrical arrangement.
- **Conclusion**: The bonds in AlF3 are equal.

4. **Analyze NF3 (Nitrogen Trifluoride)**:
- Nitrogen (N) is the central atom.
- It has 3 fluorine atoms bonded to it and 1 lone pair.
- The molecular geometry is trigonal pyramidal.
- The presence of the lone pair affects the bond angles, but the bond lengths between N and F are equal.
- **Conclusion**: The bonds in NF3 are equal.

### Final Conclusion:
Among the given options, only ClF3 has bonds that are not equal. Therefore, the answer is **option A: ClF3**.