Among the following, the group of molecules that undergoes rapid hydrolysis is

Options

A. `SF_(6), Al_(2)Cl_(6), SiMe_(4)`
B. `BCl_(3), SF_(6),SiCl_(4)`
C. `BCl_(3), SiCl_(4), PCl_(5)`
D. `SF_(6),Al_(2)Cl_(6),SiCl_(4)`

Answer

To solve the question regarding which group of molecules undergoes rapid hydrolysis, we will analyze each option provided and determine their behavior when reacted with water.

### Step 1: Analyze SF6
- **Molecule**: SF6 (Sulfur hexafluoride)
- **Analysis**: Sulfur in SF6 has a covalency of 6, and all positions are occupied by fluorine atoms. The strong electronegativity of fluorine makes it very stable and prevents hydrolysis. Therefore, SF6 does not undergo hydrolysis.

### Step 2: Analyze Al2Cl6
- **Molecule**: Al2Cl6 (Aluminum chloride dimer)
- **Analysis**: Al2Cl6 exists as a dimer, which means it is not readily available for hydrolysis. The presence of the dimeric structure hinders the addition of water molecules, making hydrolysis not possible.

### Step 3: Analyze BCl3
- **Molecule**: BCl3 (Boron trichloride)
- **Analysis**: BCl3 can undergo hydrolysis. When water is added, it reacts to form boric acid (H3BO3) and hydrochloric acid (HCl). The reaction can be represented as:
\[ BCl3 + 3H2O \rightarrow H3BO3 + 3HCl \]
This indicates that BCl3 undergoes rapid hydrolysis.

### Step 4: Analyze SiCl4
- **Molecule**: SiCl4 (Silicon tetrachloride)
- **Analysis**: SiCl4 also undergoes hydrolysis. When water is added, it reacts to form silicic acid (Si(OH)4) and hydrochloric acid (HCl). The reaction can be represented as:
\[ SiCl4 + 4H2O \rightarrow Si(OH)4 + 4HCl \]
This indicates that SiCl4 undergoes rapid hydrolysis.

### Step 5: Analyze PCl5
- **Molecule**: PCl5 (Phosphorus pentachloride)
- **Analysis**: PCl5 undergoes hydrolysis as well. When water is added, it first forms phosphorus oxychloride (POCl3) and hydrochloric acid (HCl). The reaction can be represented as:
\[ PCl5 + H2O \rightarrow POCl3 + 3HCl \]
If excess water is added, it further reacts to form phosphoric acid (H3PO4):
\[ POCl3 + 3H2O \rightarrow H3PO4 + 3HCl \]
This indicates that PCl5 also undergoes rapid hydrolysis.

### Conclusion
Based on the analysis, the group of molecules that undergoes rapid hydrolysis is:
- **BCl3, SiCl4, and PCl5**

### Final Answer
The correct answer is: **BCl3, SiCl4, and PCl5**.