Name the members of the lanthanoid series which exhibit +4 oxidation and those which exhibit +2 oxidation states. This type of behaviour with electronic configuration of these elements ?

Explanation

`+4` oxidation State = `""_(58)Ce, ""_(59)Pr , ""_(60)Nd, ""_(65)Th, ""_(66)Dy`
`+2` Oxidation State = `""_(60)Nd, ""_(62)Sm, ""_(63)Eu, ""_(69)Tm, ""_(70)Yb `
In general, +2 oxidation state is exhibited by the elements with configuration `5d^0 6s^2` so that two electron may be easily lost. Similarly +4 oxidation state is shown by the elements which after losing four electron acquire configuration either close to `4f^0` or close to `4f^7`.