In PbS + 4H₂O₂ → PbSO₄ + 4H₂O, which species is the reducing agent?
PbS (S: -2 to +6 in PbSO₄) loses electrons, reducing H₂O₂ (O: -1 to -2).
Ref: NCERT Class 11 Chemistry > Chapter 7: Redox Reactions > Topic: Oxidizing and Reducing Agents and Strength