The molecule which has the largest dipole moment amongst the following is

Options

A. `CH_4`
B. `CHCl_3`
C. `C Cl_4`
D. `CH_2Cl_2`

Answer

To determine which molecule has the largest dipole moment among the given options, we will analyze each molecule step by step.

### Step 1: Understand Dipole Moment
The dipole moment (\( \mu \)) of a molecule is a measure of the separation of positive and negative charges in the molecule. It is influenced by the electronegativity difference between the atoms and the molecular geometry.

### Step 2: Analyze Each Molecule
1. **CH4 (Methane)**
- **Hybridization**: sp³
- **Geometry**: Tetrahedral
- **Electronegativity**: C (2.5) and H (2.1) → Difference = 0.4
- **Dipole Moment**: The dipole moments of the C-H bonds cancel out due to symmetry.
- **Result**: \( \mu = 0 \)

2. **CHCl3 (Chloroform)**
- **Hybridization**: sp³
- **Geometry**: Tetrahedral
- **Electronegativity**: C (2.5), Cl (3.0), H (2.1)
- **Dipole Moment**: The dipole moments of the C-Cl bonds are stronger than that of C-H bonds. The resultant dipole moment is directed towards Cl.
- **Result**: \( \mu > 0 \)

3. **CCl4 (Carbon Tetrachloride)**
- **Hybridization**: sp³
- **Geometry**: Tetrahedral
- **Electronegativity**: C (2.5), Cl (3.0)
- **Dipole Moment**: The dipole moments of the C-Cl bonds cancel out due to symmetry.
- **Result**: \( \mu = 0 \)

4. **CH2Cl2 (Dichloromethane)**
- **Hybridization**: sp³
- **Geometry**: Tetrahedral
- **Electronegativity**: C (2.5), Cl (3.0), H (2.1)
- **Dipole Moment**: The dipole moments of the two C-Cl bonds do not cancel out due to the presence of two H atoms, resulting in a net dipole moment directed towards Cl.
- **Result**: \( \mu > 0 \)

### Step 3: Compare Dipole Moments
- CH4: \( \mu = 0 \)
- CHCl3: \( \mu > 0 \)
- CCl4: \( \mu = 0 \)
- CH2Cl2: \( \mu > 0 \)

Among the molecules with non-zero dipole moments, CHCl3 and CH2Cl2 both have dipole moments, but CH2Cl2 has a larger dipole moment due to the presence of two electronegative Cl atoms and two less electronegative H atoms.

### Conclusion
The molecule with the largest dipole moment is **CH2Cl2 (Dichloromethane)**.

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