The actinoids exhibit a larger number of oxidation states than the corresponding members in the lanthanoids series?

Question

 How would you account for the following :

The actinoids exhibit a larger number of oxidation states than the corresponding members in the lanthanoids series?

Answer 1

Actinoids exhibit a large number of oxidation states because 5f ,6d and 7s levels have almost comparable energies (Very small energy difference between sub shells) than the energy difference between 4f and 5d orbitals in case of lanthanoid.