Answer
$C{O_3}^{2-}$ is a weak base.
Work Step by Step
It is the conjugate base of a weak acid $HC{O_3}^-$, therefore, it is weak too.
And we can also analyze the table $14.2$ (Page 624), and see that, it has a $K_b =2.1 \times 10^{-4}$.
Compounds with $K_b < 1$, are considered weak bases.
