Question

Find the molecule/ion with the greatest potential to act as a Lewis acid ?

• A. $C{H}_3^{+}$
• B. $C{N}^{-}$
• C. $N{H}_3$
• D. $B{F}_4^{-}$
• E. $C{O}_2$

Answer 1

The correct option is A $C{H}_3^{+}$

$C{H}_3^{+}$ is the ion with the greatest potential to act as a Lewis acid. The $C$ atom has $6$ valence electrons and thus incomplete octet. It has ability to accept a pair of electrons from suitable acid.
In other molecules, $C{N}^{-},$ $N{H}_3$ , $B{F}_4^{-}$ and $C{O}_2$, all the atoms have completed their octet. Hence, none of them have tendency to accept and electron pair. Hence, they do not act as lewis acids.