The molecules which has zero dipole moment is:

Options

A. `ClO_2`
B. `PCl_3`
C. `XeF_4`
D. `CHCl_3`

Explanation

To determine which molecule has a zero dipole moment, we need to analyze the molecular structures and the electronegativity of the atoms involved. Below is a step-by-step solution to the question.

### Step-by-Step Solution:

1. **Understand Dipole Moment**:
- Dipole moment is a vector quantity that arises from the separation of positive and negative charges in a molecule. It is directed from the positive end to the negative end (from less electronegative to more electronegative atom).

2. **Analyze Each Option**:
- We will look at each molecule provided in the options to determine if they have a net dipole moment.

3. **Option 1: ClO2 (Chlorine Dioxide)**:
- Chlorine has 7 valence electrons and forms bonds with two oxygen atoms. The structure has a bent shape due to lone pairs on chlorine.
- The dipole moments from the chlorine to each oxygen do not cancel out because of the bent shape, resulting in a net dipole moment.
- **Conclusion**: ClO2 has a dipole moment ≠ 0.

4. **Option 2: PCl3 (Phosphorus Trichloride)**:
- Phosphorus has 5 valence electrons and forms three bonds with chlorine, with one lone pair on phosphorus. The geometry is trigonal pyramidal.
- The dipole moments from the phosphorus to each chlorine do not cancel out due to the lone pair, resulting in a net dipole moment.
- **Conclusion**: PCl3 has a dipole moment ≠ 0.

5. **Option 3: XeF4 (Xenon Tetrafluoride)**:
- Xenon has 8 valence electrons and forms bonds with four fluorine atoms, with two lone pairs. The structure is square planar.
- The dipole moments from xenon to each fluorine are equal and opposite, and the lone pairs also cancel each other out. Therefore, the net dipole moment is zero.
- **Conclusion**: XeF4 has a dipole moment = 0.

6. **Option 4: CHCl3 (Chloroform)**:
- Carbon has 4 valence electrons and forms one bond with hydrogen and three bonds with chlorine. The geometry is tetrahedral.
- The dipole moments from carbon to chlorine and from carbon to hydrogen do not cancel out, resulting in a net dipole moment.
- **Conclusion**: CHCl3 has a dipole moment ≠ 0.

### Final Answer:
The molecule that has a zero dipole moment is **XeF4** (Option 3).