Consider the ionic reaction : ${\mathrm{HC}}_2{\mathrm{O}}_4^{-}+{\mathrm{PO}}_4^{-3}\rightleftharpoons {\mathrm{HPO}}_4^{2-}+{\mathrm{C}}_2{\mathrm{O}}_4^{2-}$. Identify the incorrect statement(s)

${\mathrm{HC}}_2{\mathrm{O}}_4^{-}$ and ${\mathrm{C}}_2{\mathrm{O}}_4^{-2}$ are conjugate acid-base pairs

The P – O bond order in ${\mathrm{PO}}_4^{-3}$ is 1.75

The C – O bond order in ${\mathrm{C}}_2{\mathrm{O}}_4^{2-}$ is 1.50

The above equilibrium mixture can act as a buffer (both acids have nearly the same dissociation constant)