Electronic configuration of the given species are a. Sm2+(Z=62)=[Xe]4f6b.Eu2+(Z=63)=[Xe]4f7c. Yb2+(Z=70)=[Xe]4f14d.Ce2+(Z=58)=[Xe]4f15d1 On the basis of above electronic configuration, only Yb2+(Z=70) has no unpaired electrons i.e. has fully-filled orbitals. Thus it is dimagnetic in nature.