Most common oxidation state for Lanthanoid is +3. Oxidation numbers +2 and +4 do occur particularly when they lead to which of the following?

All of these

Most common oxidation state for Lanthanoid is +3. Oxidation numbers +2 and +4 do occur particularly when they lead to:

(i) A noble gas configuration (Ce⁴⁺)

(ii) A half-filled f-subshell (Eu²⁺ and Tb⁴⁺)

(iii) A completely filled f-subshell (Yb²⁺)