The spin-only magnetic moment of $Fe^{2+}$ ion (in $BM$) is approximately

Increasing order of magnetic moments of $I. [Fe(CN)_6]^{4-}$,$II. [Fe(CN)_6]^{3-}$,$III. [Cr(NH_3)_6]^{3+}$,$IV. [Ni(H_2O)_4]^{2+}$ is

The $d$ electron configurations of $Cr^{2+}, Mn^{2+}, Fe^{2+}$ and $Ni^{2+}$ are $3d^4, 3d^5, 3d^6$ and $3d^8$ respectively. Which one of the following aqua complexes will exhibit the minimum paramagnetic behaviour?
(At. No. $Cr = 24, Mn = 25, Fe = 26, Ni = 28$)

The diamagnetic species is

Which of the following compounds are colourless? ($TiF_6^{2-}, CoF_6^{3-}, Cu_2Cl_2$ and $NiCl_4^{2-}$) (Atomic numbers: $Ti = 22, Co = 27, Cu = 29, Ni = 28$)

The correct order of the increasing magnetic moments for the following ions is $NiCl_4^{2-}$,$Fe(H_2O)_6^{2+}$,$Ni(CN)_4^{2-}$,and $Cu(H_2O)_6^{2+}$.