Statement-1 : `PH_(3)` and `PF_(3)` are pyramidal in shape with one lone pair on P . But `PF_(3)` has greatest bond angle than `PH_(3)`.
and
Statement-2 : Back bonding is present in `PF_(3)` but absent in `PH_(3)`.

Options

A. (A) Statement-1 is True , Statement-2 is True , Statement-2 is a correct explanation for Statement-2
B. (B) Statement-1 is True , Statement-2 is True , Statement-2 is NOT a correct explanation for Statement-2
C. (C) Statement-1 is True , Statement-2 is False
D. (D) Statement-1 is False , Statement-2 is True

Answer

To analyze the statements regarding the molecular shapes and bond angles of PH₃ and PF₃, we can break down the solution into several steps.

### Step 1: Determine the molecular geometry of PH₃ and PF₃
- Both PH₃ and PF₃ have phosphorus (P) as the central atom with three bonded atoms and one lone pair of electrons.
- The hybridization of phosphorus in both cases is sp³, leading to a pyramidal shape due to the presence of the lone pair.

**Hint:** Remember that the presence of lone pairs affects the molecular geometry and bond angles.

### Step 2: Analyze the bond angles in PH₃ and PF₃
- In PH₃, the bond angle is approximately 93.5° due to the repulsion between the lone pair and the bonding pairs.
- In PF₃, the bond angle is larger, approximately 97°, due to the presence of back bonding.

**Hint:** Consider how lone pairs and bond pairs interact differently in terms of repulsion.

### Step 3: Understand the concept of back bonding
- Back bonding occurs when a filled p-orbital of a ligand (in this case, fluorine) overlaps with an empty d-orbital of the central atom (phosphorus).
- In PF₃, fluorine has three lone pairs and can donate one of its lone pairs to the empty d-orbital of phosphorus, increasing the bond angle due to additional repulsion.

**Hint:** Focus on how the presence of d-orbitals in phosphorus allows for back bonding, which is not possible in PH₃.

### Step 4: Compare the two statements
- **Statement 1**: "PH₃ and PF₃ are pyramidal in shape with one lone pair on P. But PF₃ has a greater bond angle than PH₃." This statement is true.
- **Statement 2**: "Back bonding is present in PF₃ but absent in PH₃." This statement is also true.

**Hint:** Verify if the explanations provided in each statement logically connect to the concepts discussed.

### Step 5: Conclusion
- Both statements are true, and Statement 2 correctly explains why PF₃ has a greater bond angle than PH₃ due to the presence of back bonding.

**Final Answer:** Both Statement 1 and Statement 2 are true, and Statement 2 is the correct explanation for Statement 1.