Which of the following is polar

Options

A. p-dichlorobenzene
B. trans-1-chloropropene
C. boron tri fluoride
D. xenon tetra fluoride

Answer

To determine which of the given molecules is polar, we need to analyze the molecular structures and their dipole moments. A polar molecule has a net dipole moment that is not zero, meaning that the distribution of electron density is uneven.

### Step-by-Step Solution:

1. **Identify the Molecules:**
We have four options to evaluate:
- Para-dichlorobenzene
- Trans-1-chloropropene
- Boron trifluoride (BF₃)
- Xenon tetrafluoride (XeF₄)

2. **Analyze Para-dichlorobenzene:**
- Structure: Benzene ring with two chlorine atoms in para positions.
- Dipole Moment: The dipole moments of the two chlorine atoms are equal in magnitude but opposite in direction, leading to cancellation.
- Conclusion: Net dipole moment = 0 (non-polar).

3. **Analyze Trans-1-chloropropene:**
- Structure: A double bond between two carbon atoms with a chlorine atom and a methyl group (CH₃) on opposite sides.
- Dipole Moment: The chlorine atom creates a dipole moment, but due to the symmetry of the molecule, the dipole moments cancel out.
- Conclusion: Net dipole moment = 0 (non-polar).

4. **Analyze Boron Trifluoride (BF₃):**
- Structure: Boron atom at the center with three fluorine atoms symmetrically arranged around it.
- Dipole Moment: The dipole moments of the three fluorine atoms cancel each other out due to symmetry.
- Conclusion: Net dipole moment = 0 (non-polar).

5. **Analyze Xenon Tetrafluoride (XeF₄):**
- Structure: Xenon atom at the center with four fluorine atoms in a square planar arrangement, and two lone pairs of electrons on xenon.
- Dipole Moment: The dipole moments of the fluorine atoms cancel each other out due to the symmetrical arrangement.
- Conclusion: Net dipole moment = 0 (non-polar).

6. **Final Conclusion:**
Since all the analyzed molecules (para-dichlorobenzene, trans-1-chloropropene, boron trifluoride, and xenon tetrafluoride) have a net dipole moment of zero, none of them are polar. If there was another option provided that was not analyzed, it might be the polar molecule. However, based on the analysis of the given options, none are polar.