The types of isomerism shown by $[Cr(NH_3)_5NO_2]Cl_2$ are:

The calculated magnetic moment value for the $Fe^{2+}$ ion in $BM$ is:

If the bidentate ligand ethane-$1, 2$-diamine $(en)$ is progressively added to a green aqueous solution of $[Ni(H_2O)_6]Cl_2$ in the molar ratios $en : Ni$ as $1 : 1, 2 : 1, 3 : 1$,then their associated spin-only magnetic moments (in $B.M.$ unit) are respectively

The spin-only magnetic moment of $[ZCl_{4}]^{2-}$ is $3.87 \, BM,$ where $Z$ is $.....$

Complex compound$(s)$ having an even number of space (stereo) isomers is/are :
(where $AA^{-}$ is a symmetrical bidentate ligand and $a, b, c, d, e$ are monodentate ligands)

Which one of the following complexes shows optical isomerism? $(en = \text{ethylenediamine})$