Which of the following compounds cannot show coordination isomerism?

Indicate the types of isomerism exhibited by the following complexes and draw the structures for these isomers:
$(i)$ $K[Cr(H_2O)_2(C_2O_4)_2]$
$(ii)$ $[Co(en)_3]Cl_3$
$(iii)$ $[Co(NH_3)_5(NO_2)](NO_3)_2$
$(iv)$ $[Pt(NH_3)(H_2O)Cl_2]$

Among $[Ni(CO)_4]$,$[NiCl_4]^{2-}$,$[Co(NH_3)_4Cl_2]Cl$,$Na_3[CoF_6]$,$Na_2O_2$ and $CsO_2$,the total number of paramagnetic compounds is

Which of the following coordination compounds would exhibit optical isomerism?

The complex(es),which can exhibit the type of isomerism shown by $[Pt(NH_3)_2 Br_2]$,is(are) [en $= H_2 NCH_2 CH_2 NH_2$ ]
$(A)$ $[Pt(en)(SCN)_2]$
$(B)$ $[Zn(NH_3)_2 Cl_2]$
$(C)$ $[Pt(NH_3)_2 Cl_4]$
$(D)$ $[Cr(en)_2(H_2 O)(SO_4)]^{+}$

How many geometrical isomers are shown by the complex $[Pt(NH_3)(NH_2OH)(H_2O)(Py)]^+$?