While sulphur dioxide and hydrogen peroxide can act as oxidising as well as reducing agents in their reactions, ozone and nitric acid act only as oxidants. Why ?

While sulphur dioxide and hydrogen peroxide can act as oxidising as we

1.	While sulphur dioxide and hydrogen peroxide can act as oxidising as well as reducing agents in their reactions, ozone and nitric acid act only as oxidants. Why ?
Answer» Solution :In `SO_(2)`, the O.S. of S is + 4. Sulphur can exhibit any oxidation state in between-2 and + 6. THEREFORE, in `SO_(2)`, it can decrease as well as increase its oxidation state, i.e., it can undergo reduction as well as oxidation. This is why `SO_(2)` can act both as an oxidising and a reducing AGENT. Same is the situation with hydrogen PEROXIDE. In `H_(2)O_(2)`, O atom is in the O.S. of -1. Oxygen can exhibit any oxidation state in between - 2 and 0 (+ 2 also when in combination with F). Therefore, in `H_(2)O_(2)`, it is free to decrease or increase its oxidation state. This is why `H_(2)O_(2)` also acts both as an oxidising and as a reducing agent. In `O_(3)`, the O.S. of O is zero. It can only decrease its oxidation state either to -1 or to -2, but can not increase its oxidation state. Therefore, `O_(3)` acts only as an oxidant. Same is the situation with nitric ACID. In `HNO_(3)`, the O.S. of N is +5, which is the highest O.S. of N. Therefore, it can only decrease its O.S. This is why `HNO_(3)` also acts only as an oxidant.