Question

In which of the following reactions of H$_2$O$_2$ acts as an oxidizing agent (either in acidic, alkaline, or neutral medium)? 
% Given Reactions 
(i) \( 2Fe^{2+} + H_2O_2 \rightarrow \) 
(ii) \( 2MnO_4^- + 6H^+ + 5H_2O_2 \rightarrow \) 
(iii) \( I_2 + H_2O_2 + 2OH^- \rightarrow \) 
(iv) \( Mn^{2+} + H_2O_2 \rightarrow \) 
 

• A. (ii), (iii)
• B. (i), (iv)
• C. (i), (iii)
• D. (ii), (iv)

Hint:

Hydrogen peroxide (\( H_2O_2 \)) is a versatile redox agent that can act as either an oxidizing or reducing agent, depending on the reaction medium.

Answer 1

The Correct Option is B

Step 1: Understanding the Role of H$_2$O$_2$ as an Oxidizing Agent 
Hydrogen peroxide (\( H_2O_2 \)) can act as both an oxidizing and a reducing agent, depending on the reaction conditions. 
In acidic and neutral conditions, it tends to act as an oxidizing agent. 
In alkaline medium, it can act as either an oxidizing or reducing agent. 
Step 2: Completing the Given Reactions 
\[ (i) \quad 2Fe^{2+} + H_2O_2 \rightarrow 2Fe^{3+} + 2OH^- \] Here, \( H_2O_2 \) acts as an oxidizing agent by converting \( Fe^{2+} \) to \( Fe^{3+} \). \[ (ii) \quad 2MnO_4^- + 6H^+ + 5H_2O_2 \rightarrow 2Mn^{2+} + 5O_2 + 8H_2O \] Here, \( H_2O_2 \) acts as a reducing agent because it is oxidized to \( O_2 \). \[ (iii) \quad I_2 + H_2O_2 + 2OH^- \rightarrow 2I^- + O_2 + 2H_2O \] Here, \( H_2O_2 \) acts as a reducing agent by reducing iodine (\( I_2 \)) to iodide (\( I^- \)). \[ (iv) \quad Mn^{2+} + H_2O_2 \rightarrow MnO_2 + 2H^+ \] Here, \( H_2O_2 \) oxidizes \( Mn^{2+} \) to \( MnO_2 \), acting as an oxidizing agent. 
Step 3: Identifying the Correct Answer 
\( H_2O_2 \) acts as an oxidizing agent in reactions (i) and (iv).