Answer 1

Actinoids have a general electronic configuration  5f^d-14 6d^0-17s². 
They are placed at the bottom of periodic table. It follows actinium, Ac = (Z = 89).
i.e., It starts from the seventh period and 3rd group.
`2"Ln" +3"S" rightarrow "Ln"_2"S"_3`      (Ln is any lanthanoids)
                  X `rightarrow ` X²⁺ +2e^-
Electronic Configuration :1s² 2s² 2p⁶3s²3p⁶4s¹3d⁵ 
in +2 state : 1s² 2s² 2p⁶3s²3p⁶4s⁰3d⁴

Number of unpaired electron = 4

Magnetic moment `(mu) = sqrt(n"("n"+2)) = sqrt(4(4+2)) = sqrt(24) =4.89` B.M