In which of the following configurations will there be the possibility of both paramagnetism and diamagnetism,depending on the nature of the ligands?

Which of the following has a non-zero magnetic moment and $sp^3d^2$ hybridization?

For octahedral $Mn(II)$ and tetrahedral $Ni(II)$ complexes,consider the following statements:
$(I)$ Both the complexes can be high spin.
$(II)$ $Ni(II)$ complex can very rarely be low spin.
$(III)$ With strong field ligands,$Mn(II)$ complexes can be low spin.
$(IV)$ Aqueous solution of $Mn(II)$ ions is yellow in color.

The metal $Ni$ $(Z = 28)$ combines with a unidentate ligand $X^-$ to form a paramagnetic complex $[NiX_4]^{2-}$. What are its geometry and the number of unpaired electrons in $Ni$?

How many unpaired electrons are present in the central metal ion of $[CoCl_4]^{2-}$?

From the magnetic behaviour of $[NiCl_4]^{2-}$ (paramagnetic) and $[Ni(CO)_4]$ (diamagnetic),choose the correct geometry and oxidation state.