Which of the following explanation is incorrect for ${\mathrm{ClO}}_4^{-}$ species?

${\mathrm{ClO}}_4^{-}$ shows disproportionation reaction

${\mathrm{ClO}}_4^{-}$ is basic in nature

${\mathrm{ClO}}_4^{-}$ does not show disproportionation reaction

The oxidation number of Cl is +7 in ${\mathrm{ClO}}_4^{-}$