Question

Given below are two statements:
Statement I: \( \text{S}_8 \) solid undergoes disproportionation reaction under alkaline conditions to form \( \text{S}^{2-} \) and \( \text{S}_2\text{O}_3^{2-} \). 
Statement II: \( \text{ClO}_4^- \) can undergo disproportionation reaction under acidic condition.
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Statement I is correct but statement II is incorrect.
• B. Statement I is incorrect but statement II is correct
• C. Both statement I and statement II are incorrect
• D. Both statement I and statement II are correct

Answer 1

The Correct Option is A

To evaluate the given statements and determine which is correct, let's analyze each statement based on known chemical reactions and principles.

1. Statement I: \(S_8\) solid undergoes disproportionation reaction under alkaline conditions to form \(S^{2-}\) and \(S_2O_3^{2-}\).
   • Disproportionation is a specific type of redox (reduction-oxidation) reaction in which a single substance is simultaneously reduced and oxidized to form two different products.
   • In alkaline conditions, elemental sulfur \((S_8)\) can actually disproportionate. The reaction is:

\(3S_8 + 6OH^- \rightarrow 2S_2O_3^{2-} + 4S^{2-} + 3H_2O\)

• This confirms that under alkaline conditions, sulfur can indeed form \(S^{2-}\) (sulfide) and \(S_2O_3^{2-}\) (thiosulfate).

1. Statement II: \(ClO_4^-\\) can undergo disproportionation reaction under acidic conditions.
   • Perchlorate ion \((ClO_4^-)\) is known for being very stable, especially under acidic conditions. It is already in its highest oxidation state, where chlorine is +7.
   • Generally, in a disproportionation reaction, a substance must be capable of existing in a higher as well as a lower oxidation state. However, chlorine in \(ClO_4^-\) cannot oxidize further (higher than +7 is unfeasible under normal conditions).
   • Therefore, no disproportionation reaction of \(ClO_4^-\) occurs under acidic conditions, confirming that Statement II is incorrect.

Based on the analysis above:

• Statement I is correct as sulfur in \(S_8\) can undergo disproportionation to form \(S^{2-}\) and \(S_2O_3^{2-}\) under alkaline conditions.
• Statement II is incorrect as \(ClO_4^-\\) does not undergo disproportionation under acidic conditions.

Therefore, the correct answer is: Statement I is correct but statement II is incorrect.

Answer 2

To determine which of the given statements are correct, let's analyze each statement individually and understand the chemical processes involved.

Statement I: \( \text{S}_8 \) solid undergoes disproportionation reaction under alkaline conditions to form \( \text{S}^{2-} \) and \( \text{S}_2\text{O}_3^{2-} \).

Disproportionation reactions involve a substance being simultaneously oxidized and reduced. The reaction for sulfur in \( \text{S}_8 \) under alkaline conditions can be represented as follows:

\[ \text{3S}_8 + \text{12OH}^- \rightarrow \text{4S}_2\text{O}_3^{2-} + \text{2S}^{2-} + \text{6H}_2\text{O} \]

In this reaction:

• Sulfur is reduced from \( \text{S}_8 \) (0 oxidation state) to \( \text{S}^{2-} \) (-2 oxidation state).
• Sulfur is also oxidized from \( \text{S}_8 \) (0 oxidation state) to \( \text{S}_2\text{O}_3^{2-} \) (+2.5 oxidation state).

This confirms that \( \text{S}_8 \) undergoes a disproportionation reaction under alkaline conditions. Hence, Statement I is correct.

Statement II: \( \text{ClO}_4^- \) can undergo disproportionation reaction under acidic condition.

\( \text{ClO}_4^- \), or perchlorate ion, is already in its highest oxidation state (+7 for chlorine). In a disproportionation reaction, an element must be able to undergo both oxidation and reduction. Since chlorine in \( \text{ClO}_4^- \) is in its highest oxidation state, it cannot be oxidized further; hence, it cannot participate in a disproportionation reaction under normal conditions, regardless of the acidity of the medium.

Therefore, Statement II is incorrect.

Conclusion:

Based on the analysis:

• Statement I is correct because \( \text{S}_8 \) indeed undergoes disproportionation under alkaline conditions to form \( \text{S}^{2-} \) and \( \text{S}_2\text{O}_3^{2-} \).
• Statement II is incorrect as \( \text{ClO}_4^- \) cannot undergo disproportionation under any condition.

Thus, the correct answer is: Statement I is correct but statement II is incorrect.