Increasing order of dipole moment is `H_2O, NH_3, NF_3 and C Cl_4` is

Options

A. `C Cl_4 lt NF_3 lt NH_3 lt H_2O`
B. `C Cl_4 gt NF_3 gt NH_3 gt H_2O`
C. `NF_3 gt H_2O gt C Cl_4 gt H_2O`
D. all the four have equal dipole moments

Answer

To determine the increasing order of dipole moments for the molecules \( H_2O, NH_3, NF_3, \) and \( CCl_4 \), we need to analyze the molecular structures and the electronegativity of the atoms involved. Here’s a step-by-step solution:

### Step 1: Understand Dipole Moment
The dipole moment (\( \mu \)) is a measure of the polarity of a molecule and is defined as:
\[ \mu = q \cdot d \]
where \( q \) is the charge and \( d \) is the distance between the charges. A higher dipole moment indicates a more polar molecule.

### Step 2: Analyze Each Molecule
1. **Water (\( H_2O \))**:
- Structure: Bent shape due to two lone pairs on oxygen.
- Electronegativity: Oxygen is more electronegative than hydrogen, creating a significant dipole moment.
- Result: High dipole moment.

2. **Ammonia (\( NH_3 \))**:
- Structure: Trigonal pyramidal shape due to one lone pair on nitrogen.
- Electronegativity: Nitrogen is more electronegative than hydrogen but less than oxygen.
- Result: Moderate dipole moment.

3. **Nitrogen Trifluoride (\( NF_3 \))**:
- Structure: Trigonal pyramidal due to one lone pair on nitrogen.
- Electronegativity: Fluorine is highly electronegative, but the dipole moments of the \( N-F \) bonds partially cancel out due to the molecular geometry.
- Result: Lower dipole moment than \( NH_3 \).

4. **Carbon Tetrachloride (\( CCl_4 \))**:
- Structure: Tetrahedral shape with no lone pairs.
- Electronegativity: Chlorine is more electronegative than carbon, but the symmetrical shape leads to cancellation of dipole moments.
- Result: Zero dipole moment (non-polar).

### Step 3: Compare Dipole Moments
Based on the analysis:
- \( CCl_4 \) has a dipole moment of 0 (non-polar).
- \( NF_3 \) has a lower dipole moment than \( NH_3 \).
- \( NH_3 \) has a higher dipole moment than \( NF_3 \).
- \( H_2O \) has the highest dipole moment.

### Conclusion: Increasing Order of Dipole Moment
The increasing order of dipole moments for the given molecules is:
\[ CCl_4 < NF_3 < NH_3 < H_2O \]