`PCl_5` in solid state exists as.

Options

A. `[PBr_4]^(+) [PBr_(6)]^(-)`
B. `[PBr_(5)]^(+) [PBr_(5)]^(-)`
C. `[PBr_(4)]^(+) [Br^(-)]`
D. `PBr_(5)`

Answer

To determine the state of phosphorus pentachloride (PCl₅) in its solid form, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Physical State of PCl₅**:
- Phosphorus pentachloride (PCl₅) exists in different physical states depending on the conditions. In the solid state, it forms a specific structure.

2. **Describe the Appearance of Solid PCl₅**:
- Solid PCl₅ is typically described as a pale yellow crystalline substance. This characteristic color is important for identification.

3. **Understand the Ionic Forms**:
- In the solid state, PCl₅ can be represented in terms of its ionic forms. It exists as a cation (PCl₄⁺) and an anion (PCl₆⁻). This ionic representation is crucial in understanding its behavior in the solid state.

4. **Explain the Hybridization**:
- The cationic form (PCl₄⁺) has a tetrahedral geometry due to sp³ hybridization, while the anionic form (PCl₆⁻) adopts an octahedral geometry due to sp³d² hybridization.

5. **Summarize the Key Points**:
- Therefore, in its solid state, PCl₅ exists as a pale yellow crystalline solid, with cationic and anionic forms contributing to its structure.

### Final Answer:
Phosphorus pentachloride (PCl₅) in solid state exists as a pale yellow crystalline solid, with the ionic forms PCl₄⁺ (tetrahedral) and PCl₆⁻ (octahedral).

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