Question

Which of the following is not a disproportionation reaction?

• A. \( \text{Hg}_2\text{Cl}_2 \rightarrow \text{Hg} + \text{HgCl}_2 \)
• B. \( 4\text{H}_3\text{PO}_3 \rightarrow 3\text{H}_3\text{PO}_4 + \text{PH}_3 \)
• C. \( \text{Cl}_2 + 2\text{NaOH} \rightarrow \text{NaCl} + \text{NaOCl} + \text{H}_2\text{O} \)
• D. \( \text{BaO}_2 + \text{H}_2\text{SO}_4 \rightarrow \text{BaSO}_4 + \text{H}_2\text{O}_2 \)

Hint:

Disproportionation requires the same element to undergo both oxidation and reduction. Check oxidation states to confirm.

Answer 1

The Correct Option is D

A disproportionation reaction involves a single element undergoing both oxidation and reduction.
Let’s evaluate:
- (1) Mercury is both oxidized and reduced → disproportionation.
- (2) Phosphorous in \( \text{H}_3\text{PO}_3 \) splits into \( \text{H}_3\text{PO}_4 \) (oxidized) and \( \text{PH}_3 \) (reduced) → disproportionation.
- (3) Chlorine changes to both \( \text{Cl}^- \) and \( \text{ClO}^- \) → disproportionation.
- (4) No single element changes oxidation state; this is a simple double displacement reaction.