The radical in this question is OH.
The reason this will be a radical, is that the definition of a radical is the presence of an unpaired electron. This causes the radical to be unstable, desperately wanting to do something with the free electron that it has.
Oxygen has a charge of 2-, and Hydrogen has a charge of +1. When you pair them, you end up with a net charge of 1-, which is the presence of that unpaired electron. It will usually be written as: 
Answer:
in the nucleus of eukaryotic organisms
They arrive after P waves.
They travel through solids.
S waves (Secondary or Shear waves) are known to be type of waves that travel through the solid and also travel slower when compared with P-waves. S-waves are refers to as shear waves because they don’t change the volume of the materials through which they travel or propagate, they shear it. Furthermore, S-waves are transverse waves because they vibrate ground in transverse direction or perpendicular to the direction in which the waves travels.
