the correct statement is

Options

A. `BI_(3)` is the weakest Lewis acid among the boron halides
B. there is minimum `ppi- ppi` back bonding in `BF_(3)`
C. `BF_(3)` is the strongest Lewis acid among the other boron halides
D. there is maximum `ppi-ppi` back bonding in `BF_(3)`.

Explanation

To determine the correct statement regarding boron halides, we need to analyze the properties of the boron halides: BF3, BCl3, and BI3, particularly focusing on their Lewis acidity and the extent of pi (π) back bonding.

### Step-by-Step Solution:

1. **Understanding Lewis Acids**:
- Lewis acids are species that can accept an electron pair. The strength of a Lewis acid is often related to its ability to stabilize the positive charge after accepting an electron pair.

2. **Analyzing Boron Halides**:
- The boron halides in question are BF3, BCl3, and BI3.
- BF3 is known for its strong Lewis acidity due to the high electronegativity of fluorine, which allows for effective back bonding.

3. **Back Bonding**:
- Back bonding occurs when the halogen atom donates a pair of electrons to the empty p-orbital of boron. This stabilizes the molecule and affects its Lewis acidity.
- BF3 has significant back bonding due to the small size and high electronegativity of fluorine, which allows for effective overlap of orbitals.

4. **Comparing Lewis Acidity**:
- BF3 is the strongest Lewis acid among the boron halides because of its ability to engage in back bonding.
- BCl3 is less acidic than BF3 but more acidic than BI3. BI3 has the weakest Lewis acidity due to the larger size of iodine, which results in less effective back bonding.

5. **Conclusion**:
- The correct statements are:
- BI3 is the weakest Lewis acid among the boron halides.
- BF3 has maximum π back bonding, making it the strongest Lewis acid.

### Final Answer:
The correct statement is: **BI3 is the weakest Lewis acid among the boron halides, and BF3 exhibits maximum π back bonding, making it the strongest Lewis acid.**