Question

Why does cerium show +4 oxidation state?

Answer 1

General and the most stable oxidation state of Lanthanide is +3. But some of the elements also show +2,+4 etc oxidation states. These extra oxidation states are stable due to the presence of either half filled or fully filled or empty f sub shell.
Cerium shows +4 oxidation state.. Cerium has the atomic number=58.
Electronic configuration = 1s²2s²2p⁶3s^​23p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁶4f¹5d¹6s²
Cerium shows +3, and +4 oxidation state. The +4 oxidation state is shown because after losing 1 electron from the f sub shell, it attain a noble gas configuration.
So cerium shows +4 oxidation state.