Arrange the following molecules from most to least polar.
`underset("I")(CH_(4))underset("II")(CF_(2)Cl_(2))underset("III")(CF_(2)H_(2))underset("IV")("CCl"_(4))underset("V")(CH_(2)Cl_(2))`

Options

A. III gt V gt II gt I = IV
B. II gt IV gt III gt IV gt I
C. III gt II gt V gt IV gt I
D. V gt III gt II gt IV gt I

Answer

To determine the polarity of the given molecules, we need to analyze their molecular geometry and the electronegativity of the atoms involved. The molecules to be considered are:

1. CH₄ (Methane)
2. CF₂Cl₂ (Dichlorodifluoromethane)
3. CF₂H₂ (Difluoromethane)
4. CCl₄ (Carbon tetrachloride)
5. CH₂Cl₂ (Dichloromethane)

### Step-by-Step Solution:

**Step 1: Analyze CH₄ (Methane)**
- **Geometry**: Tetrahedral
- **Electronegativity**: All hydrogen atoms are identical, and the molecule is symmetrical.
- **Polarity**: Non-polar (net dipole moment = 0).

**Step 2: Analyze CCl₄ (Carbon Tetrachloride)**
- **Geometry**: Tetrahedral
- **Electronegativity**: Chlorine is more electronegative than carbon, but the molecule is symmetrical.
- **Polarity**: Non-polar (net dipole moment = 0).

**Step 3: Analyze CF₂Cl₂ (Dichlorodifluoromethane)**
- **Geometry**: Tetrahedral
- **Electronegativity**: Fluorine is highly electronegative, pulling electron density towards itself. Chlorine is also electronegative but less than fluorine.
- **Polarity**: Polar (net dipole moment directed towards the fluorine atoms).

**Step 4: Analyze CF₂H₂ (Difluoromethane)**
- **Geometry**: Tetrahedral
- **Electronegativity**: The two fluorine atoms are highly electronegative, pulling electron density towards themselves.
- **Polarity**: More polar than CF₂Cl₂ due to the presence of two fluorine atoms (net dipole moment directed towards the fluorine atoms).

**Step 5: Analyze CH₂Cl₂ (Dichloromethane)**
- **Geometry**: Tetrahedral
- **Electronegativity**: Chlorine is more electronegative than hydrogen, resulting in a net dipole moment towards the chlorine atoms.
- **Polarity**: Polar, but less polar than CF₂H₂ and CF₂Cl₂.

### Final Arrangement from Most to Least Polar:
1. **CF₂H₂ (III)** - Most polar due to two highly electronegative fluorine atoms.
2. **CF₂Cl₂ (II)** - Polar due to the presence of fluorine and chlorine.
3. **CH₂Cl₂ (V)** - Polar but less than CF₂Cl₂.
4. **CCl₄ (IV)** - Non-polar due to symmetry.
5. **CH₄ (I)** - Least polar (non-polar).

### Summary:
The order from most to least polar is:
**CF₂H₂ (III) > CF₂Cl₂ (II) > CH₂Cl₂ (V) > CCl₄ (IV) > CH₄ (I)**