In which of the following reactions of ( H ₂ O ₂ ) acts as an oxidising agent (either in acidic, alkaline or neutral medium)? (i) (2 Fe ²⁺+ H ₂ O ₂ ) (ii) (2 MnO ₄⁻+6 H ⁺+5 H ₂ O ₂ ) (iii) ( I ₂+ H ₂ O ₂+2 OH ⁻ ) (iv) ( Mn ²⁺+ H ₂ O ₂ )

Step-by-step solution

Let us complete the reactions : (i) ( Fe ²⁺+ H ₂ O ₂⁻ Fe ³⁺+ H ₂ O ²⁻ ) (ii) ( Mn ⁷⁺ O ₄⁻+ H ⁺+ H ₂ O ₂⁻ Mn ²⁺+ O ₂^0+ H ₂ O ) (iii) ( I ₂^0+ H ₂ O ₂⁻+ OH ⁻ I ⁻+ O ₂^0+ H ₂ O ) (iv) ( Mn ²⁺+ H ₂ O ₂⁻ Mn ⁴⁺+ OH ⁻ ) In reactions, ( Fe ²⁺ ) of (i) and ( Mn ²⁺ ) of (iv) get oxidised to ( Fe ³⁺ ) and ( Mn ⁴⁺ ) respectively by ( H ₂ O ₂ ), which itself is reduced to ( H ₂ O ).