The electronic configuration of each element is as follows, La(Z=57)=[Xe]545d16s2 U(Z=92)=[Rn]865f36d17s2 Lr(Z=103)=[Rn]865f146d17s2 Th(Z=90)=[Rn]865f146d17s2 Ac(Z=89)=[Rn]866d17s2 Ce(Z=58)=[Xe]544f15d1Gs2 Therefore, La, Ac and Th do not have f-electrons.