The correct order of the dipole moment is :

Options

A. `CH_(4)gtNF_(3)gtNH_(3)gtH_(2)O`
B. `NF_(3)gtCH_(4)gtNH_(3)gtH_(2)O`
C. `NH_(3)gtNF_(3)gtCH_(4)gtH_(2)O`
D. `H_(2)OgtNH_(3)gtNF_(3)gtCH_(4)`

Answer

To determine the correct order of dipole moments for the molecules CH4, NF3, NH3, and H2O, we can follow these steps:

### Step 1: Understand Dipole Moment
The dipole moment is a measure of the separation of positive and negative charges in a molecule. It depends on the electronegativity of the atoms involved and the geometry of the molecule.

**Hint:** Remember that dipole moment is influenced by both the electronegativity difference between bonded atoms and the molecular geometry.

### Step 2: Analyze CH4 (Methane)
- **Structure:** Tetrahedral
- **Electronegativity:** Carbon (2.5) and Hydrogen (2.2)
- **Dipole Moment:** Due to its symmetrical tetrahedral shape, the dipole moments of the C-H bonds cancel each other out, resulting in a net dipole moment of zero.

**Hint:** Symmetry in molecular geometry can lead to a net dipole moment of zero.

### Step 3: Analyze NF3 (Nitrogen Trifluoride)
- **Structure:** Trigonal pyramidal
- **Electronegativity:** Nitrogen (3.0) and Fluorine (4.0)
- **Dipole Moment:** The molecule has a lone pair on nitrogen, and the dipole moments of the N-F bonds do not completely cancel out due to the geometry, resulting in a net dipole moment.

**Hint:** Lone pairs can affect the molecular shape and the resultant dipole moment.

### Step 4: Analyze NH3 (Ammonia)
- **Structure:** Trigonal pyramidal
- **Electronegativity:** Nitrogen (3.0) and Hydrogen (2.2)
- **Dipole Moment:** Similar to NF3, NH3 has a lone pair on nitrogen, and the dipole moments from the N-H bonds add up in the direction of the lone pair, resulting in a significant dipole moment.

**Hint:** The presence of lone pairs can enhance the dipole moment if the bond dipoles are aligned in the same direction.

### Step 5: Analyze H2O (Water)
- **Structure:** Bent
- **Electronegativity:** Oxygen (3.5) and Hydrogen (2.2)
- **Dipole Moment:** Water has two lone pairs on oxygen, and the bent shape means that the dipole moments from the O-H bonds add up effectively, resulting in a higher dipole moment than NH3 and NF3.

**Hint:** The bent shape of water contributes to a stronger overall dipole moment due to the additive nature of the bond dipoles.

### Step 6: Compare Dipole Moments
- **CH4:** 0 (zero dipole moment)
- **NF3:** Moderate dipole moment
- **NH3:** Higher dipole moment than NF3
- **H2O:** Highest dipole moment

### Step 7: Order the Dipole Moments
Based on the analysis:
1. **CH4:** 0
2. **NF3:** Moderate
3. **NH3:** Higher
4. **H2O:** Highest

Thus, the correct order of dipole moments is:
**CH4 < NF3 < NH3 < H2O**

**Final Answer:** The correct order of the dipole moment is CH4 < NF3 < NH3 < H2O.