The total possible coordination isomers for the following compounds respectively are :
$[Co(en)_3] [Cr(C_2O_4)_3]$
$[Cu(NH_3)_4] [CuCl_4]$
$[Ni(en)_3] [Co(NO_2)_6]$

The complex cation which has two isomers is:

The number of possible optical isomers for the complexes $MA_{2}B_{2}$ with $sp^{3}$ and $dsp^{2}$ hybridised metal atom,respectively,is.
Note : $A$ and $B$ are unidentate neutral and unidentate monoanionic ligands,respectively.

Which of the following pairs of isomers and their types of isomerism are correctly matched?
$1.$ $[Co(NH_3)_5NO_2]Cl_2$ and $[Co(NH_3)_5ONO]Cl_2$ $-$ Linkage
$2.$ $[Cu(NH_3)_4] [PtCl_4]$ and $[Pt(NH_3)_4] [CuCl_4]$ $-$ Coordination
$3.$ $[Pt(NH_3)_4Cl_2]Br_2$ and $[Pt(NH_3)_4Br_2]Cl_2$ $-$ Ionization

Identify the correct pair of properties of the $[Co(NH_3)_6]^{3+}$ complex ion.

The compound$(s)$ that exhibit$(s)$ geometrical isomerism is(are):
$A$. $[Pt(en)Cl_2]$
$B$. $[Pt(en)_2]Cl_2$
$C$. $[Pt(en)_2Cl_2]Cl_2$
$D$. $[Pt(NH_3)_2Cl_2]$