Rapid Hydrolysis of Molecules

Hydrolysis involves the reaction of a substance with water, often breaking chemical bonds. The question asks to identify a group of molecules exhibiting rapid hydrolysis.

Hydrolysis of $BCl_3$, $SiCl_4$, and $PCl_5$

These molecules undergo rapid hydrolysis due to specific chemical properties:

• $BCl_3$: Boron is electron-deficient (Lewis acidic) and susceptible to nucleophilic attack by water. The B-Cl bonds are polarized. $ BCl_3 + 3H_2O \rightarrow B(OH)_3 + 3HCl $
• $SiCl_4$: Silicon tetrachloride has polar Si-Cl bonds. Silicon can expand its octet using d-orbitals, facilitating nucleophilic attack by water. $ SiCl_4 + 4H_2O \rightarrow Si(OH)_4 + 4HCl $
• $PCl_5$: Phosphorus pentachloride features polar P-Cl bonds. The central phosphorus atom can accommodate more than eight electrons, making it reactive towards water. $ PCl_5 + 4H_2O \rightarrow H_3PO_4 + 5HCl $

Hydrolysis Resistance of $SF_6$, $SiMe_4$

Molecules like $SF_6$ and $SiMe_4$ resist rapid hydrolysis:

• $SF_6$: Highly stable due to strong S-F bonds and significant steric hindrance around the sulfur atom, preventing water molecule access.
• $SiMe_4$: Silicon-carbon bonds are strong and non-polar relative to Si-Cl bonds, making them resistant to hydrolytic cleavage.

Group Showing Rapid Hydrolysis

Considering these factors, the group $BCl_3$, $SiCl_4$, $PCl_5$ represents molecules that undergo rapid hydrolysis.