Chemistry - CHEMICAL BONDING Question with Solution | TestHub

The incorrect reactions are (B) and (C) because of back-bonding effects that reduce the availability of lone pairs:

Reaction (B): In (SiH₃)₂O, the lone pairs on Oxygen are involved in $p\pi -d\pi$ back-bonding with the empty $d$-orbitals of Silicon. This makes Oxygen a poor Lewis base, so it does not react with the Lewis acid BF₃.

Reaction (C): Similarly, in (SiH₃)₃N, the lone pair on Nitrogen is delocalized into the empty $d$-orbitals of Silicon. The molecule becomes planar and non-basic, preventing it from reacting with HCl.

Reactions (A) & (D): These are correct as (CH₃)₂O has available lone pairs (no back-bonding), and BF₃ readily accepts F⁻ to form the stable $[B{F}_4{]}^{-}$ ion.