Why does `O_3` act as a powerful oxidising agent?

Explanation

Ozone is not a very stable compound under normal conditions and decomposes readily on heating to give a molecule of oxygen and nascent oxygen. Nascent oxygen, being a free radical, is very reactive.
`underset("Ozone")(O_(3)) overset(Delta) to underset("Oxygen") (O_(2)) + underset("Nascent oxygen")([O])`
Therefore, ozone acts as a powerful oxidising agent.