Of the following,which is diamagnetic in nature?

The magnetic moment (in $\mu_{B}$) of $[Ni(dimethylglyoximate)_{2}]$ complex is closest to $......$

The correct increasing order of spin-only magnetic moment values of the complex ions $[MnBr_{4}]^{2-}$ $(A)$, $[Cu(H_{2}O)_{6}]^{2+}$ $(B)$, $[Ni(CN)_{4}]^{2-}$ $(C)$ and $[Ni(H_{2}O)_{6}]^{2+}$ $(D)$ is:

Identify the number of complexes that are optically active:
$[Co(en)_3]^{3+}$; $[Co(NH_3)_4Cl_2]^{+}$; $[CoCl_2(en)_2]^{+}$; $[Co(NH_3)_3(NO_2)_3]$

The complex having the highest spin-only magnetic moment is

The complex which has facial $(fac)$ and meridional $(mer)$ isomers is
(Given: $py = \text{pyridine}$ and $en = H_2N-CH_2-CH_2-NH_2$)