All the following molecules are polar except one

Options

A. `BCl_(3)`
B. `CH_(2)Cl_(2)`
C. `NH_(3)`
D. `FNO`

Explanation

To determine which of the given molecules is nonpolar, we need to analyze the molecular geometry and the electronegativity of the atoms involved in each molecule. A molecule is considered nonpolar if its dipole moment (μ) is equal to zero, which usually occurs in symmetric molecules where the individual bond dipoles cancel each other out.

### Step-by-Step Solution:

1. **Identify the Molecules**: We have four molecules to analyze:
- A) BCl3 (Boron Trichloride)
- B) CH2Cl2 (Dichloromethane)
- C) NH3 (Ammonia)
- D) FNO (Fluoroamine)

2. **Analyze BCl3**:
- **Structure**: BCl3 has a trigonal planar geometry with boron at the center and three chlorine atoms at the corners.
- **Symmetry**: The molecule is symmetric, and the bond dipoles from the B-Cl bonds cancel each other out.
- **Dipole Moment**: Since the structure is symmetric, the net dipole moment (μ) is equal to zero.
- **Conclusion**: BCl3 is nonpolar.

3. **Analyze CH2Cl2**:
- **Structure**: CH2Cl2 has a tetrahedral geometry with carbon at the center, two hydrogen atoms, and two chlorine atoms.
- **Symmetry**: The molecule is not symmetric due to the different electronegativities of hydrogen and chlorine.
- **Dipole Moment**: The bond dipoles do not cancel out, resulting in a net dipole moment (μ) that is not equal to zero.
- **Conclusion**: CH2Cl2 is polar.

4. **Analyze NH3**:
- **Structure**: NH3 also has a tetrahedral geometry (specifically a trigonal pyramidal shape).
- **Symmetry**: The molecule is not symmetric because of the presence of a lone pair on nitrogen.
- **Dipole Moment**: The bond dipoles do not cancel out, leading to a net dipole moment (μ) that is not equal to zero.
- **Conclusion**: NH3 is polar.

5. **Analyze FNO**:
- **Structure**: FNO has a bent structure due to the presence of a lone pair on nitrogen.
- **Symmetry**: The molecule is not symmetric, and the electronegativity difference between fluorine and oxygen contributes to the dipole moment.
- **Dipole Moment**: The bond dipoles do not cancel out, resulting in a net dipole moment (μ) that is not equal to zero.
- **Conclusion**: FNO is polar.

### Final Conclusion:
The only nonpolar molecule among the options is **A) BCl3**.

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