Question

Which of the following is an example of disproportionation redox reaction? 

• A. $N_2(g) + O_2(g) ⇢ 2NO(g) $
• B. $2NO_2(g) +2OH^{-} ⇢ NO_2^{-} (aq) +NO_3^{-} (aq) + H_2O(I)$
• C. $2Pb(NO_3)_2(s) ⇢ 2PbO(s) + 4NO_2(g) + O_2(g)$
• D. $NaH(s) + H_2O(l) ⇢ NaOH(aq) + H_2(g)$
• E. $2H_2(g) + O_2(g) ⇢ 2H_2O(l)$

Answer 1

The Correct Option is B

Which of the following is an example of disproportionation redox reaction?

A disproportionation reaction is a redox reaction in which the same element is both oxidized and reduced.

Let's analyze the options:

1. \( N_2(g) + O_2(g) \rightarrow 2NO(g) \)
   – Both elements are oxidized; this is not a disproportionation.
2. \( 2NO_2(g) + 2OH^{-} \rightarrow NO_2^{-}(aq) + NO_3^{-}(aq) + H_2O(l) \)
   – This is a disproportionation reaction: nitrogen in NO₂ is both oxidized to NO₃⁻ and reduced to NO₂⁻.
3. \( 2Pb(NO_3)_2(s) \rightarrow 2PbO(s) + 4NO_2(g) + O_2(g) \)
   – This is thermal decomposition, not a disproportionation.
4. \( NaH(s) + H_2O(l) \rightarrow NaOH(aq) + H_2(g) \)
   – This is a simple reaction between a hydride and water.
5. \( 2H_2(g) + O_2(g) \rightarrow 2H_2O(l) \)
   – This is a normal redox reaction, not disproportionation.

Correct Answer: \( 2NO_2(g) + 2OH^{-} \rightarrow NO_2^{-}(aq) + NO_3^{-}(aq) + H_2O(l) \)