In which of the following cases dipole moment will be highest ?

Options

A. `CH_(3)-CF_(3)`
B. `FCH_(2)-CH_(2)F`
C. `F_(2)C = CF_(2)`
D. `CF_(3) - CF_(3)`

Answer

To determine which of the given compounds has the highest dipole moment, we need to analyze the molecular structures and the electronegativities of the atoms involved in each case.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are CH3CF3, CH2F, CF2CF2, and CF3CF3.

2. **Analyze CH3CF3**:
- Structure: One carbon (C) is bonded to three fluorine (F) atoms and another carbon (C) is bonded to three hydrogen (H) atoms.
- Electronegativity: Fluorine is more electronegative than carbon and hydrogen.
- Dipole Moments:
- The dipole moment from C-H bonds points towards carbon.
- The dipole moment from C-F bonds points towards fluorine.
- Result: The net dipole moment is directed towards the fluorine atoms, indicating a significant dipole moment.

3. **Analyze CH2F**:
- Structure: This compound has one carbon atom bonded to two hydrogen atoms and one fluorine atom.
- Dipole Moment: The dipole moment from the C-F bond points towards fluorine, while the dipole moments from the C-H bonds point towards carbon.
- Result: The net dipole moment is directed towards fluorine, but it is less than that of CH3CF3 due to fewer polar bonds.

4. **Analyze CF2CF2**:
- Structure: Two carbon atoms, each bonded to two fluorine atoms.
- Dipole Moments: The dipole moments from each C-F bond point towards the fluorine atoms.
- Result: The dipole moments cancel each other out because they are equal and opposite, resulting in a net dipole moment of zero.

5. **Analyze CF3CF3**:
- Structure: Two carbon atoms, each bonded to three fluorine atoms.
- Dipole Moments: Similar to CF2CF2, the dipole moments from each C-F bond cancel each other out.
- Result: The net dipole moment is also zero.

6. **Conclusion**:
- Among the compounds analyzed, CH3CF3 has the highest dipole moment due to the presence of multiple polar bonds and the net direction of dipole moments pointing towards the fluorine atoms.

### Final Answer:
The compound with the highest dipole moment is **CH3CF3**.