Find out the incorrect order of the dipole moment among the following pair of compound

Options

A. `NH_(3) gt NF_(3)`
B. p-dichloro benzene ` gt ` o-dichloro benzene
C. `CH_(3)Cl gt CH_(2)Cl_(2)`
D. `SiF_(4)lt SF_(4)`

Answer

To solve the question regarding the incorrect order of dipole moments among the given compounds, we will analyze each pair step by step.

### Step 1: Analyze NH3 vs. NF3
- **NH3 (Ammonia)** has a pyramidal structure with a lone pair on nitrogen. The dipole moments of the N-H bonds add up because they are directed towards the more electronegative nitrogen atom, resulting in a net dipole moment.
- **NF3 (Nitrogen Trifluoride)** also has a pyramidal structure, but the dipole moments of the N-F bonds are directed towards the fluorine atoms, which are more electronegative. The presence of the lone pair on nitrogen causes some cancellation of the dipole moments.
- **Conclusion**: NH3 has a greater dipole moment than NF3. This statement is correct.

### Step 2: Analyze para-Dichlorobenzene vs. ortho-Dichlorobenzene
- **Para-Dichlorobenzene** has two chlorine atoms positioned opposite each other on the benzene ring, leading to a symmetrical structure. The dipole moments of the C-Cl bonds cancel each other out, resulting in a net dipole moment of zero.
- **Ortho-Dichlorobenzene** has the chlorine atoms adjacent to each other, leading to a net dipole moment because the dipole moments do not completely cancel out.
- **Conclusion**: Para-Dichlorobenzene has a dipole moment of zero, while ortho-Dichlorobenzene has a net dipole moment greater than zero. This statement is incorrect.

### Step 3: Analyze CH3Cl vs. CH2Cl2
- **CH3Cl (Methyl Chloride)** has three C-H bonds and one C-Cl bond. The dipole moment is influenced by the C-Cl bond, which is stronger than the C-H bonds.
- **CH2Cl2 (Dichloromethane)** has two C-Cl bonds and two C-H bonds. The dipole moments of the C-Cl bonds will dominate, leading to a higher overall dipole moment compared to CH3Cl.
- **Conclusion**: CH2Cl2 has a greater dipole moment than CH3Cl. This statement is correct.

### Step 4: Analyze SiF4 vs. SF4
- **SiF4 (Silicon Tetrafluoride)** has a tetrahedral structure, which is symmetrical. Therefore, the dipole moments of the Si-F bonds cancel out, resulting in a net dipole moment of zero.
- **SF4 (Sulfur Tetrafluoride)** has a seesaw geometry due to the presence of a lone pair on sulfur. This geometry leads to a net dipole moment because the dipole moments do not cancel completely.
- **Conclusion**: SiF4 has a dipole moment of zero, while SF4 has a net dipole moment. This statement is correct.

### Final Conclusion
The only incorrect order of dipole moments is in the comparison of para-Dichlorobenzene and ortho-Dichlorobenzene, where para-Dichlorobenzene has a dipole moment of zero, while ortho-Dichlorobenzene has a net dipole moment greater than zero.

### Answer
The incorrect order of dipole moment is in option **B** (para-Dichlorobenzene vs. ortho-Dichlorobenzene).