Chemistry - Ionic Equilibrium Question with Solution | TestHub

${\mathrm{ClO}}_4^{-}<{\mathrm{ClO}}_3^{-}<{\mathrm{ClO}}_2^{-}<{\mathrm{ClO}}^{-}$ is the correct increasing order of Bronsted base. With increase in the number of oxygen atoms in the conjugate bases, the delocalisation of the $\pi$ bond becomes more and more extended. This results in decrease in the electron density. Consequently basicity also decreases.