Which of the following is not a free radical, but it is a reactive oxygen species?
Most powerful oxygen free radical is Hydroxyradical.
Least powerful Reactive Oxygen species(ROS) is Hydrogen peroxide.
Precursor of all Reactive Oxygen species is Superoxide radical.
H2O2 is not a free radical,  but a ROS.

Reference- Review of biochemistry Pg-411
Hydroxyradical
Hydrogen peroxide
Superoxide radical
Both 1 & 2