The species which does not undergo disproportionation reaction is :

We need to identify the species that does NOT undergo a disproportionation reaction among the given chlorine oxyanions.

A disproportionation reaction is one in which the same element is simultaneously oxidised and reduced. For a species to undergo disproportionation, the element must be in an intermediate oxidation state so that it can go both up and down in oxidation state.

- $$ClO^-$$ (hypochlorite): Cl is in +1 oxidation state

- $$ClO_2^-$$ (chlorite): Cl is in +3 oxidation state

- $$ClO_3^-$$ (chlorate): Cl is in +5 oxidation state

- $$ClO_4^-$$ (perchlorate): Cl is in +7 oxidation state

For disproportionation to occur, the element must be able to both increase and decrease its oxidation state. The range of chlorine oxidation states is from -1 (in $$Cl^-$$) to +7 (in $$ClO_4^-$$).

- $$ClO^-$$ (+1): Can go up (to +3, +5, +7) and down (to 0, -1). Can disproportionate. Example: $$3ClO^- \rightarrow ClO_3^- + 2Cl^-$$

- $$ClO_2^-$$ (+3): Can go up and down. Can disproportionate.

- $$ClO_3^-$$ (+5): Can go up and down. Can disproportionate.

- $$ClO_4^-$$ (+7): This is the highest oxidation state of chlorine. It cannot be oxidised further. Since it can only be reduced (not oxidised), it cannot undergo disproportionation.

The correct answer is Option (4): $$ClO_4^-$$.