Among the complex ions,$[Co(en)_2Cl_2]^{+}$,$[CrCl_2(C_2O_4)_2]^{3-}$,$[Fe(H_2O)_4(OH)_2]^{+}$,$[Fe(NH_3)_2(CN)_4]^{-}$,$[Co(en)_2(NH_3)Cl]^{2+}$ and $[Co(NH_3)_4(H_2O)Cl]^{2+}$,the number of complex ion$(s)$ that show$(s)$ cis-trans isomerism 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 pairs of complexes are coordination isomers?

For the octahedral complexes of $Fe^{3+}$ in $SCN^{-}$ (thiocyanato-$S$) and in $CN^{-}$ ligand environments,the difference between the spin-only magnetic moments in Bohr magnetons (when approximated to the nearest integer) is
[Atomic number of $Fe = 26$]

Which of the following complexes will exhibit optical isomerism?

The number of possible stereoisomers for the complex $[Co(en)_2Cl_2]Cl$ is $(en = \text{ethylenediamine})$.