Which of the following species cannot act as both an oxidizing and a reducing agent?

Step-by-step solution

For a species to act as both an oxidizing and a reducing agent, the element undergoing the redox change must be in an intermediate oxidation state. Let us calculate the oxidation state of the key element in each species: 1) In H ₂ O ₂ , the oxidation state of oxygen is -1 . It can be oxidized to 0 (in O ₂ ) or reduced to -2 (in H ₂ O ). 2) In SO ₂ , the oxidation state of sulphur is +4 . It can be oxidized to +6 or reduced to lower states. 3) In HNO ₃ , the oxidation state of nitrogen is +5 . This is the maximum po