Which from following lanthanoids exhibits +4 oxidation state in F ^7 configuration?

Step-by-step solution

To identify the lanthanoid with a +4 oxidation state and an f ^7 configuration, examine the electron structure of each ion. Cerium ( Z = 58 ), with configuration [ Xe ] 4 f ^1 5 d ^1 6 s ^2 , forms Ce ⁴⁺ as [ Xe ] , not f ^7 . Ytterbium ( Z = 70 ), [ Xe ] 4 f ¹⁴ 6 s ^2 , yields Yb ⁴⁺ as [ Xe ] 4 f ¹² , deviating from f ^7 . Europium ( Z = 63 ), [ Xe ] 4 f ^7 6 s ^2 , produces Eu ⁴⁺ as [ Xe ] 4 f ^5 , not matching; though Eu ²⁺ is f ^7 . Terbium ( Z = 65 ), [ Xe ] 4 f ^9 6 s ^2 , loses two 6 s and two 4 f electrons