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

There are four complexes of $Ni$. Select the complex(es) which will be attracted by a magnetic field:
$(I) \ [Ni(CN)_4]^{2-}, \ (II) \ [NiCl_4]^{2-}, \ (III) \ [Ni(CO)_4]$
$(IV) \ [Ni(H_2O)_6]^{2+}$

Which kind of isomerism is exhibited by the octahedral complex $Co(NH_3)_4Br_2Cl$?

Given below are two statements:
Statement $I$: $A$ homoleptic octahedral complex,formed using monodentate ligands,will not show stereoisomerism.
Statement $II$: $cis-$ and $trans-$ platin are heteroleptic complexes of $Pd$.
In the light of the above statements,choose the correct answer from the options given below.

Match List-$I$ with List-$II$ :

List-$I$ (Complexes)	List-$II$ (Types)
$a$. $[Co(NH_3)_5NO_2]Cl_2$ and $[Co(NH_3)_5ONO]Cl_2$	$i$. Linkage isomerism
$b$. $[Cr(NH_3)_6][Co(CN)_6]$ and $[Cr(CN)_6][Co(NH_3)_6]$	$ii$. Coordination isomerism
$c$. $[Co(NH_3)_5(SO_4)]Br$ and $[Co(NH_3)_5Br]SO_4$	$iii$. Ionisation isomerism
$d$. $[Cr(H_2O)_6]Cl_3$ and $[Cr(H_2O)_5Cl]Cl_2 \cdot H_2O$	$iv$. Solvate isomerism

Choose the correct answer from the options given below :

The number of optical isomers possible for $[Cr(C_{2}O_{4})_{3}]^{3-}$ is $.....$ .