Statement-1. `BF_(3)` is a weaker Lewis acid than `BCl_(3)`.
Statement-2. The `ppi-ppi` back bonding is stronger in `BF_(3)` than in `BCl_(3)`.

Options

A. Statement-1 is True, Statement-2 is True , Statement-2 is a correct explanation for statement-1.
B. Statement-1 is True, Statement-2 is True , Statement-2 is not a correct explanation for statement-1.
C. Statement-1 is True, Statement-2 is False.
D. Statement-1 is False, Statement-2 is True.

Answer

To analyze the statements provided in the question, we can break down the reasoning step by step.

### Step 1: Understanding Lewis Acids
A Lewis acid is defined as a species that can accept an electron pair. The strength of a Lewis acid is influenced by the ability of the central atom to accept electrons.

### Step 2: Comparing BF3 and BCl3
- **BF3 (Boron Trifluoride)**: Boron has an empty p-orbital and can accept electron pairs. However, fluorine is highly electronegative, which means it pulls electron density away from boron, making it less effective at accepting electrons.
- **BCl3 (Boron Trichloride)**: Chlorine is less electronegative than fluorine, which means it does not withdraw electron density from boron as strongly as fluorine does. This allows boron in BCl3 to be more effective at accepting electron pairs.

### Conclusion from Step 1 and Step 2
From the above analysis, we can conclude that BF3 is indeed a weaker Lewis acid than BCl3. Thus, **Statement 1 is true**.

### Step 3: Understanding Back Bonding
Back bonding occurs when there is a donation of electron density from filled p-orbitals of a ligand (like fluorine or chlorine) to an empty orbital of the central atom (boron in this case).

### Step 4: Comparing Back Bonding in BF3 and BCl3
- **In BF3**: The fluorine atoms have lone pairs that can be donated to the empty p-orbital of boron. The high electronegativity of fluorine allows for significant back donation, which stabilizes the molecule.
- **In BCl3**: Chlorine, being less electronegative, does not engage in back bonding as effectively as fluorine. The back donation is weaker compared to BF3.

### Conclusion from Step 3 and Step 4
Since the back bonding is stronger in BF3 due to the electronegativity of fluorine, **Statement 2 is false**.

### Final Conclusion
- **Statement 1 is true**: BF3 is a weaker Lewis acid than BCl3.
- **Statement 2 is false**: The back bonding is not stronger in BF3 than in BCl3; it is actually stronger in BCl3.

### Summary of the Statements
- **Statement 1**: True
- **Statement 2**: False