$[Co(NH_3)_5SO_4]Br$ and $[Co(NH_3)_5Br]SO_4$ are a pair of which isomers?

The "spin only" magnetic moment of $Ni^{2+}$ in aqueous solution would be [At. no. of $Ni = 28$]

The number of geometric isomers possible for the complex $[CoL_2 Cl_2]^{-}$ where $L = H_2NCH_2CH_2O^{-}$ is

The existence of two different colored complexes of $[Co(NH_3)_4Cl_2]^+$ is due to which of the following?

Among $(i)$ $[Cr(en)_{3}]^{3+}$,$(ii)$ $trans-[Cr(en)_{2}Cl_{2}]^{+}$,$(iii)$ $cis-[Cr(en)_{2}Cl_{2}]^{+}$,$(iv)$ $[Co(NH_{3})_{4}Cl_{2}]^{+}$,the optically active complexes are:

Which of the following ligands is able to form linkage isomers?