What is disproportionation?

A disproportionation reaction is one in which the same species undergoes both:

• oxidation to a higher oxidation state, and
• reduction to a lower oxidation state.

Therefore, a species can undergo disproportionation only if its element is in an intermediate oxidation state — not in the highest or lowest possible oxidation state.

Find oxidation state of Cl in each species

Let oxidation state of chlorine be $x$.

A. $\mathrm{ClO}_4^-$ $x + 4(-2) = -1$ $x - 8 = -1$ $x = +7$

B. $\mathrm{ClO}_3^-$ $x + 3(-2) = -1$ $x - 6 = -1$ $x = +5$

C. $\mathrm{ClO}^-$ $x + (-2) = -1$ $x = +1$

D. $\mathrm{ClO}_2^-$ $x + 2(-2) = -1$ $x - 4 = -1$ $x = +3$

Analyze possibility of disproportionation

Chlorine commonly shows oxidation states from $-1$ to $+7$.

• $\mathrm{ClO}_4^-$ has Cl in +7, which is the maximum oxidation state of chlorine.

  • It cannot be oxidized further.
  • Hence it cannot undergo disproportionation.

• $\mathrm{ClO}_3^-$ has Cl in +5, an intermediate state.

  • It can be oxidized to $+7$ and reduced to lower states.
  • So disproportionation is possible.

• $\mathrm{ClO}^-$ has Cl in +1, an intermediate state.

  • It can disproportionate, for example into chloride and chlorate.

• $\mathrm{ClO}_2^-$ has Cl in +3, also an intermediate state.

  • It can undergo disproportionation.

Conclusion

The species that does not undergo disproportionation is: $\boxed{\mathrm{ClO}_4^-}$

Comparison with stored correct answer

Stored correct answer: A

Our derived answer: A

Hence, the derived answer agrees with the stored correct answer.