Dipole moment of `NF_(3)` is smaller than :

Options

A. `NH_(3)`
B. `CO_(2)`
C. `BF_(3)`
D. `C Cl_(4)`

Answer

To determine which molecule has a dipole moment smaller than that of NF₃, we will analyze the dipole moments of the given options: NH₃, CO₂, BF₃, and CCl₄.

### Step-by-Step Solution:

1. **Understanding the Structure of NF₃**:
- NF₃ (Nitrogen trifluoride) has a nitrogen atom at the center with three fluorine atoms bonded to it and one lone pair of electrons on nitrogen.
- The electronegativity of fluorine is higher than that of nitrogen, which means the dipole moments from the N-F bonds point towards the fluorine atoms.

2. **Calculating the Dipole Moment of NF₃**:
- The dipole moment due to the lone pair on nitrogen points upwards.
- The resultant dipole moment of NF₃ is the vector sum of the dipole moments of the three N-F bonds and the lone pair. This results in a net dipole moment directed towards the fluorine atoms but slightly influenced by the lone pair.

3. **Analyzing NH₃ (Ammonia)**:
- NH₃ has nitrogen at the center, one lone pair above, and three hydrogen atoms.
- The dipole moments from the N-H bonds point towards nitrogen (since nitrogen is more electronegative than hydrogen).
- The lone pair also contributes to the dipole moment, resulting in a net dipole moment directed upwards.
- The dipole moment of NH₃ is higher than that of NF₃.

4. **Analyzing CO₂ (Carbon Dioxide)**:
- CO₂ is a linear molecule with the structure O=C=O.
- The dipole moments from the C=O bonds are equal in magnitude but opposite in direction, which cancels each other out.
- Therefore, the dipole moment of CO₂ is zero.

5. **Analyzing BF₃ (Boron Trifluoride)**:
- BF₃ has a trigonal planar structure with boron at the center and three fluorine atoms.
- Similar to CO₂, the dipole moments from the B-F bonds cancel each other out due to symmetry.
- Thus, the dipole moment of BF₃ is also zero.

6. **Analyzing CCl₄ (Carbon Tetrachloride)**:
- CCl₄ has a tetrahedral structure with carbon at the center and four chlorine atoms.
- The dipole moments from the C-Cl bonds also cancel out due to symmetry.
- Therefore, the dipole moment of CCl₄ is zero.

7. **Conclusion**:
- Among the options, only NH₃ has a dipole moment that is greater than that of NF₃, while CO₂, BF₃, and CCl₄ have zero dipole moments.
- Hence, the dipole moment of NF₃ is smaller than that of NH₃.

### Final Answer:
The dipole moment of NF₃ is smaller than that of **NH₃**.