The number of isomers of $[Co(dien)Cl_3]$ is

Consider the following statements and select the correct option using the codes given.
$(i)$ $[Cr(NH_3)_6][Cr(CN)_6]$ and $[Cr(NH_3)_4(CN)_2][Cr(NH_3)_2(CN)_4]$ are coordination isomers.
$(ii)$ $[Cr(py)_2(H_2O)_2Cl_2]Cl$ and $[Cr(py)_2(H_2O)Cl_3]H_2O$ are linkage isomers.
$(iii)$ $[Pt(NH_3)_4Br_2]Cl_2$ and $[Pt(NH_3)_4Cl_2]Br_2$ are linkage isomers.
$(iv)$ $[NiCl_2(PPh_3)_2]$ (tetrahedral) exhibits geometrical isomerism.

Which of the following spin paramagnetic complexes shows both geometrical and optical isomerism?

Arrange the following coordination compounds in the increasing order of magnetic moments. (Atomic numbers: $Mn = 25$; $Fe = 26$)
$(A)$ $[FeF_{6}]^{3-}$
$(B)$ $[Fe(CN)_{6}]^{3-}$
$(C)$ $[MnCl_{6}]^{3-}$ (high spin)
$(D)$ $[Mn(CN)_{6}]^{3-}$

Which of the following ions are optically active?

The total number of isomers for a square planar complex $[M(F)(Cl)(SCN)(NO_2)]$ is