How do you determine which oxidizing agent is stronger?
Look at the electronegativity values.
Oxidation is the removal of electrons from an atom or polyatomic ion.
The higher the electronegativity the greater the pull an oxidizing agent has for electrons. The higher the pull for electrons the stronger the oxidizing agent. So the element with the highest electronegativity is the strongest oxidizing agent.
You compare their standard reduction potentials.
For example, potassium permanganate and hydrogen peroxide are oxidizing agents. Which is stronger?
Look up their standard reduction potentials. We find
The one with the more positive reduction potential is the stronger oxidizing agent.
Thus, hydrogen peroxide is the stronger oxidizing agent.