Which of the following species do not show disproportionation reaction?

Question

Accepted Answer

Option 1, $ClO_{4}^{-}$, is the correct answer because it does not show a disproportionation reaction. Disproportionation reactions involve a single substance being simultaneously oxidized and reduced to form two different products. For a species to undergo disproportionation, it must be in an oxidation state that allows it to be both oxidized and reduced.

1. **Explanation for Option 1 ($ClO_{4}^{-}$):**
   - The perchlorate ion, $ClO_{4}^{-}$, has chlorine in its highest oxidation state of +7. In this state, chlorine cannot be further oxidized because it is already at its maximum oxidation state. Therefore, $ClO_{4}^{-}$ cannot undergo a disproportionation reaction as it cannot be oxidized further, and reduction alone does not constitute disproportionation.

2. **Explanation for Option 2 ($ClO_{3}^{-}$):**
   - The chlorate ion, $ClO_{3}^{-}$, has chlorine in the +5 oxidation state. It can undergo disproportionation because it can be both oxidized to $ClO_{4}^{-}$ (where chlorine is in the +7 state) and reduced to $ClO_{2}^{-}$ or $Cl^{-}$ (where chlorine is in a lower oxidation state).

3. **Explanation for Option 3 ($ClO_{2}^{-}$):**
   - The chlorite ion, $ClO_{2}^{-}$, has chlorine in the +3 oxidation state. It can undergo disproportionation as it can be oxidized to $ClO_{3}^{-}$ or $ClO_{4}^{-}$ and reduced to $Cl^{-}$.

4. **Explanation for Option 4 ($ClO^{-}$):**
   - The hypochlorite ion, $ClO^{-}$, has chlorine in the +1 oxidation state. It can undergo disproportionation because it can be oxidized to $ClO_{2}^{-}$ or $ClO_{3}^{-}$ and reduced to $Cl^{-}$.

In summary, $ClO_{4}^{-}$ is the only species among the given options that cannot undergo a disproportionation reaction due to chlorine being in its highest oxidation state, making Option 1 the correct answer.