Hydrogen peroxide (H₂O₂) can act as both an oxidizing agent and a reducing agent because the oxygen atom in H₂O₂ has an oxidation state of -1, which can either decrease to -2 (reduction, oxidizing agent) or increase to 0 (oxidation, reducing agent). A reducing agent loses electrons and gets oxidized.

Let's analyze each reaction:

Option (a): H₂O₂ + 2H⁺ + 2e^- → 2H₂O

Here, H₂O₂ gains electrons (reduction), so it acts as an oxidizing agent, not a reducing agent.

Option (b): H₂O₂ - 2e^- → O₂ + 2H⁺

H₂O₂ loses electrons (oxidation), so it acts as a reducing agent. The oxidation state of oxygen increases from -1 in H₂O₂ to 0 in O₂.

Option (c): H₂O₂ + 2e^- → 2OH^-

H₂O₂ gains electrons (reduction), so it acts as an oxidizing agent. The oxidation state of oxygen decreases from -1 to -2.

Option (d): H₂O₂ + 2OH^- - 2e^- → O₂ + 2H₂O

H₂O₂ loses electrons (oxidation), so it acts as a reducing agent. The oxidation state of oxygen increases from -1 to 0.

Thus, the reactions where H₂O₂ acts as a reducing agent are (b) and (d).

Final Answer: (b), (d)

Related Topics

Redox Reactions: Reactions involving transfer of electrons between species. An oxidizing agent gains electrons and gets reduced, while a reducing agent loses electrons and gets oxidized.

Hydrogen Peroxide: A compound that can exhibit both oxidizing and reducing behavior due to the intermediate oxidation state of oxygen (-1).

Formulae

Change in oxidation state indicates redox behavior:

If oxidation state increases → Oxidation (reducing agent)

If oxidation state decreases → Reduction (oxidizing agent)