Name the member of the lanthanoids series which exhibit+4 oxidation states and those which exhibit+2 oxidation state. Try to correlate this types of behavior with the electronic configuration of these elements.

Explanation

+4 oxidation state is exhibited by :
Ce (58), Pr (59), Nd (60), Tb (65) and Dy (66) This oxidation state is exhibited by element which acquire configuration close to `4f^0 (e.g., 4f^(0) 4f^1, or 4f^2)` and `4f^7 (e.g., 4f^7 or 4f^8)`.
+2 oxi