Which of the following compounds have zero dipole moment ?

Options

A. `BF_(3)`
B. `SnCl_(2)`
C. `H_(2)O`
D. `NH_(3)`

Answer

To determine which of the given compounds have a zero dipole moment, we will analyze each compound based on its molecular geometry and the electronegativity of the atoms involved.

### Step-by-Step Solution:

1. **Understanding Dipole Moment**:
- A dipole moment arises due to the separation of positive and negative charges in a molecule. It is a vector quantity, meaning it has both magnitude and direction. The dipole moment is influenced by the electronegativity differences between atoms and the molecular geometry.

2. **Analyzing BF3**:
- **Hybridization and Geometry**: BF3 (Boron Trifluoride) has sp² hybridization and a trigonal planar geometry.
- **Electronegativity**: Boron (B) is less electronegative than Fluorine (F), leading to a partial positive charge on boron and partial negative charges on the fluorine atoms.
- **Resultant Dipole Moment**: The dipole moments of the three B-F bonds point towards the fluorine atoms. However, due to the symmetrical trigonal planar shape, these dipole moments cancel each other out, resulting in a net dipole moment of zero.
- **Conclusion**: BF3 has a zero dipole moment.

3. **Analyzing SnCl2**:
- **Hybridization and Geometry**: SnCl2 (Tin Dichloride) has sp³ hybridization and a bent shape due to the presence of lone pairs on the tin atom.
- **Electronegativity**: Chlorine is more electronegative than tin, leading to partial negative charges on the chlorine atoms and a partial positive charge on tin.
- **Resultant Dipole Moment**: The dipole moments do not cancel due to the bent shape, resulting in a net dipole moment that is not zero.
- **Conclusion**: SnCl2 does not have a zero dipole moment.

4. **Analyzing H2O**:
- **Hybridization and Geometry**: H2O (Water) has sp³ hybridization and a bent shape.
- **Electronegativity**: Oxygen is more electronegative than hydrogen, resulting in partial negative charges on oxygen and partial positive charges on hydrogen.
- **Resultant Dipole Moment**: The dipole moments do not cancel due to the bent shape, leading to a net dipole moment that is not zero.
- **Conclusion**: H2O does not have a zero dipole moment.

5. **Analyzing NH3**:
- **Hybridization and Geometry**: NH3 (Ammonia) has sp³ hybridization and a trigonal pyramidal shape.
- **Electronegativity**: Nitrogen is more electronegative than hydrogen, resulting in a partial negative charge on nitrogen and partial positive charges on hydrogen.
- **Resultant Dipole Moment**: The dipole moments do not cancel due to the pyramidal shape, resulting in a net dipole moment that is not zero.
- **Conclusion**: NH3 does not have a zero dipole moment.

### Final Conclusion:
Among the given compounds, only **BF3** has a zero dipole moment. Therefore, the correct answer is **Option 1: BF3**.