Select correct order between following compounds:

Options

A. `NH_(3)gtNF_(3)`: bond angle
B. `NH_(3) gtNF_(3)` : dipole moment
C. `NH_(3)gtNF_(3)` %s-character of lone pair
D. `NH_(3)gtNF_(3)` : reactivity towards lewis acid

Answer

To determine the correct order between the compounds NH3 (ammonia) and NF3 (nitrogen trifluoride), we need to analyze several properties: bond angles, dipole moments, and reactivity towards Lewis acids.

### Step 1: Analyze the Molecular Geometry
Both NH3 and NF3 have a tetrahedral electron geometry due to the presence of three bonded atoms and one lone pair on nitrogen. However, the molecular geometry is trigonal pyramidal for both compounds.

### Step 2: Determine the Bond Angles
- **NH3**: The ideal tetrahedral bond angle is 109.5 degrees. However, due to the presence of a lone pair, the bond angle is reduced. The bond angle in NH3 is approximately 107 degrees.
- **NF3**: Similarly, NF3 also has a tetrahedral arrangement, but the bond angle is affected more by the electronegativity of fluorine. The bond angle in NF3 is approximately 102 degrees.

### Step 3: Compare the Bond Angles
From the analysis:
- NH3 has a bond angle of about 107 degrees.
- NF3 has a bond angle of about 102 degrees.
Thus, the bond angle in NH3 is greater than that in NF3.

### Step 4: Analyze the Dipole Moments
- **NH3**: Nitrogen is more electronegative than hydrogen, creating a dipole moment directed towards nitrogen. The dipole moment of NH3 is approximately 1.46 D (Debye).
- **NF3**: Fluorine is highly electronegative, and the dipole moment is directed towards fluorine. However, due to the geometry and the lone pair on nitrogen, the overall dipole moment is reduced to about 0.24 D.

### Step 5: Compare the Dipole Moments
- NH3 has a dipole moment of 1.46 D, which is significantly higher than NF3's dipole moment of 0.24 D. Therefore, NH3 is more polar than NF3.

### Step 6: Reactivity Towards Lewis Acids
- **NH3**: The lone pair on nitrogen is readily available for donation to Lewis acids, making NH3 a good Lewis base.
- **NF3**: The lone pair on nitrogen is less available due to the strong electronegativity of fluorine, which withdraws electron density. Thus, NF3 is less reactive as a Lewis base compared to NH3.

### Conclusion
Based on the bond angles, dipole moments, and reactivity towards Lewis acids, we can summarize:
- **Bond Angles**: NH3 > NF3
- **Dipole Moments**: NH3 > NF3
- **Reactivity**: NH3 > NF3

### Final Order
The correct order between the compounds NH3 and NF3 is:
**NH3 > NF3**