In which of the following reactions, H2O2 is acting as a reducing agent ?
SO2+H2O2⟶H2SO4
2KI+H2O2⟶2KOH+I2
PbS+4H2O2⟶PbSO4+4H2O
Ag2O+H2O2⟶2Ag+H2O+O2
H2O2 if self be oxidized to O2