Decreasing order of dipole moment in CHCl3, CCl4 & CH4 is –

Options

A. `CH Cl _ 3 gt C Cl _ 4 = CH _ 4 `
B. ` CHCl _ 3 gt C Cl _ 4 gt CH _ 4 `
C. ` C Cl _ 4 gt CHCl _ 3 gt CH _ 4 `
D. `C Cl _ 4 = CH _ 4 gt CH Cl _ 3 `

Answer

To determine the decreasing order of dipole moments in CHCl3 (chloroform), CCl4 (carbon tetrachloride), and CH4 (methane), we can analyze the molecular structures and their symmetry.

### Step-by-Step Solution:

1. **Identify the Molecular Structures**:
- **CHCl3 (Chloroform)**: This molecule has one hydrogen atom and three chlorine atoms bonded to a central carbon atom. The structure is tetrahedral.
- **CCl4 (Carbon Tetrachloride)**: This molecule has four chlorine atoms bonded to a central carbon atom, also forming a tetrahedral structure.
- **CH4 (Methane)**: This molecule has four hydrogen atoms bonded to a central carbon atom, forming a tetrahedral structure.

2. **Determine Hybridization**:
- All three molecules (CHCl3, CCl4, and CH4) have a carbon atom that is sp³ hybridized, leading to a tetrahedral geometry.

3. **Analyze Symmetry**:
- **CCl4**: The molecule is symmetrical because all four substituents (Cl) are identical. The dipole moments from each C-Cl bond cancel each other out, resulting in a net dipole moment of **0**.
- **CH4**: Similar to CCl4, methane is symmetrical with four identical hydrogen atoms. The dipole moments from each C-H bond also cancel out, resulting in a net dipole moment of **0**.
- **CHCl3**: This molecule is not symmetrical due to the presence of one hydrogen atom and three chlorine atoms. The dipole moments from the C-Cl bonds do not cancel out with the C-H bond, leading to a net dipole moment that is greater than **0**.

4. **Compare the Dipole Moments**:
- Since both CCl4 and CH4 have a dipole moment of **0**, while CHCl3 has a positive dipole moment, we can conclude:
- **Dipole Moment of CHCl3 > Dipole Moment of CCl4 = Dipole Moment of CH4 = 0**.

5. **Final Order**:
- The decreasing order of dipole moments is:
- **CHCl3 > CCl4 = CH4**.

### Conclusion:
The decreasing order of dipole moment in CHCl3, CCl4, and CH4 is:
**CHCl3 > CCl4 = CH4**.