Consider the reactions

(A) H₂O₂ + 2HI → I₂ + 2H₂O

(B) HOCl + H₂O₂→ H₃ O⁺ + Cl^- + O₂

Which of the following statements is correct about H₂O₂ with reference to these reactions? Hydrogen perioxide is _______

An oxidising agent is one which oxidises(oxidation number increases) others and itself gets reduced. Whereas a reducing agent reduces (oxidation number decreases) others and itself gets oxidised.

So, we can see that H₂O₂ acts as an oxidising agent in (A) as it increases the oxidation number of I^- in HI from -1 to 0 in I_2.

Similarly, H₂O₂ acts as a reducing agent in (B) as it decreases the oxidation number of Cl⁺ in HOCl from +1 to -1 in Cl^-.