Among `ClO^(-), ClO_(2)^(-), ClO_(3)^(-), ClO_(4)^(-)` which one cannot disproportionate and why ?

Explanation

`ClO_(4)^(-)` cannot disproportionate because in this oxonation chlorine is present in its highest oxidation state. Remaining three oxoanions undergo disproportionation because in these chlorine is in intermediate oxidation state.
`3overset((+1))(Cl)O^(-) overset(Delta)rarr 2overset((+1))(Cl^(-)) + overset((+5))(Cl)O_(3)^(-), 6overset((+3))(Cl)O_(2)^(-) overset(h v)rarr 4overset((+5))(Cl)O_(3)^(-) + 2overset((-1))(Cl^(-)), 4overset((+5))(Cl)O_(3)^(-) rarr overset((-1))(Cl^(-)) + 3 overset((+7))(Cl)O_(4)^(-)`