1) The complex showing a spin-only magnetic moment of 2.82 B.M. is: A) $Ni(CO)_{4}$ B) $[NiCl_{4}]^{2-}$ C) $Ni(PPh_{3})_{4}$ D) $[NiCN_{4}]^{2-}$ Answer: Option BExplanation:$[NiCl_{4}]^{2-}$, O.S. of Ni = +2 Ni(28) = 3d8 4S2 No. of unpaired electrons = 2 Magnetic moment, μ = 2.82 B.M.