Identify correct statement regarding `NH_(3) and BF_(3)`

Options

A. Both are Lewis acid
B. Both are iso structural
C. Both are Lewis base
D. Have different values of dipole moment

Answer

To identify the correct statement regarding NH₃ (ammonia) and BF₃ (boron trifluoride), we will analyze the properties of both compounds step by step.

### Step 1: Identify the nature of NH₃ and BF₃
- **NH₃ (Ammonia)**: It is a Lewis base because it has a lone pair of electrons on the nitrogen atom that can be donated to an electron-deficient species.
- **BF₃ (Boron Trifluoride)**: It is a Lewis acid because it has an incomplete octet and can accept a pair of electrons.

**Hint**: Remember that Lewis acids accept electron pairs, while Lewis bases donate electron pairs.

### Step 2: Analyze their structures
- **NH₃**: The molecular geometry is trigonal pyramidal due to the presence of a lone pair on nitrogen. The bond angles are approximately 107 degrees.
- **BF₃**: The molecular geometry is trigonal planar as it has no lone pairs on boron. The bond angles are 120 degrees.

**Hint**: Consider the VSEPR theory to determine the shapes of molecules based on electron pair repulsion.

### Step 3: Check if they are isostructural
- Since NH₃ has a trigonal pyramidal shape and BF₃ has a trigonal planar shape, they are not isostructural.

**Hint**: Isostructural compounds have the same molecular geometry and bond angles.

### Step 4: Evaluate the dipole moments
- **NH₃**: Due to the electronegativity difference between nitrogen and hydrogen, NH₃ has a net dipole moment that is not zero.
- **BF₃**: The symmetry of the molecule results in the dipole moments of the B-F bonds canceling each other out, leading to a net dipole moment of zero.

**Hint**: The dipole moment depends on both the bond polarity and the molecular geometry.

### Conclusion
Based on the analysis:
1. NH₃ is a Lewis base, and BF₃ is a Lewis acid (first option is incorrect).
2. NH₃ and BF₃ are not isostructural (second option is incorrect).
3. Both have different values of dipole moments (this is the correct statement).

### Final Answer
The correct statement regarding NH₃ and BF₃ is: **They have different values of dipole moment.**