The Lewis acids are electron pair acceptors due to the availability of vacant orbitals they accept electrons from the donor compounds.
- [tex](CH_3CH_2)_2CH^{+}[/tex] is a Lewis acid due to the unfilled valence shell on carbon atom (possessing positive charge) it accepts electron readily.
- [tex]CCl_{3}^{-}[/tex] is not a Lewis acid due to the presence of negative charge which represents that there are electrons available for donation.
- [tex]CH_3NH_2[/tex] is not a Lewis acid due to the presence of lone pair on nitrogen which is easily donated to the acceptors.
- [tex]BBr_3[/tex] is a Lewis acid due to the availability of vacant p-orbital on boron atom.
Hence, [tex](CH_3CH_2)_2CH^{+}[/tex] and [tex]BBr_3[/tex] are Lewis acids.
