Indicate the complex or complex ion which does not show any geometrical isomerism:

How many pairs of enantiomers are possible for the following complex compound,$[M(AB)(CD)ef]^{n \pm}$ (where $AB, CD$ are unsymmetrical bidentate ligands,and $e, f$ are monodentate ligands)?

The 'Spin only' magnetic moment for $[Ni(NH_3)_6]^{2+}$ is $ . . . . . . \times 10^{-1} \ BM$.
(Given: Atomic number of $Ni = 28$)

What type of isomerism is exhibited by $[Co(NH_3)_6][Cr(CN)_6]$ and $[Cr(NH_3)_6][Co(CN)_6]$?

Select the correct statement$(s)$ regarding the $[Ni(DMG)_2]$ complex compound.

Although $Cr^{3+}$ and $Co^{2+}$ ions have the same number of unpaired electrons,why is the magnetic moment of $Cr^{3+}$ $3.87 \ B.M.$ and that of $Co^{2+}$ $4.87 \ B.M.?$