In the following questions, a statement of assertion (A) is followed by a statement of reason (R )
A : All P-Cl bond lengths are equal in `PCl_(3)` but different in `PCl_(5)`
R : Hybrid state of central atom is different in both molecules.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements , then mark (4).

Answer

To solve the assertion and reason question regarding the bond lengths in PCl₃ and PCl₅, we need to analyze both statements carefully.

### Step 1: Analyze the Assertion (A)
The assertion states that "All P-Cl bond lengths are equal in PCl₃ but different in PCl₅."

- **For PCl₃**: Phosphorus trichloride (PCl₃) has a trigonal pyramidal structure due to the presence of one lone pair on phosphorus. The hybridization of phosphorus in PCl₃ is sp³, which means that all three P-Cl bonds are formed using equivalent sp³ hybrid orbitals. Therefore, all P-Cl bond lengths in PCl₃ are indeed equal.

- **For PCl₅**: Phosphorus pentachloride (PCl₅) has a trigonal bipyramidal structure. The hybridization of phosphorus in PCl₅ is sp³d. In this structure, there are two types of P-Cl bonds: axial and equatorial. The axial bonds (the bonds that are perpendicular to the equatorial plane) are longer than the equatorial bonds due to differences in the spatial arrangement and the s character of the orbitals involved. Thus, the bond lengths in PCl₅ are different.

### Conclusion for Assertion
The assertion is **true** because all P-Cl bond lengths are equal in PCl₃ and different in PCl₅.

### Step 2: Analyze the Reason (R)
The reason states that "The hybrid state of the central atom is different in both molecules."

- In PCl₃, the hybridization is sp³, while in PCl₅, the hybridization is sp³d. This indicates that the hybridization states of the central atom (phosphorus) are indeed different in both molecules.

### Conclusion for Reason
The reason is also **true** because the hybridization states of phosphorus in PCl₃ and PCl₅ are different.

### Step 3: Determine the Relationship Between Assertion and Reason
Now we need to determine if the reason correctly explains the assertion.

- While both statements are true, the reason provided does not directly explain why the bond lengths are equal in PCl₃ and different in PCl₅. The difference in bond lengths is due to the geometry and the nature of the hybrid orbitals involved, rather than just the hybridization state itself.

### Final Conclusion
- The assertion is true.
- The reason is true but does not provide the correct explanation for the assertion.

### Answer
Both statements are true, but the reason is not the correct explanation for the assertion.

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