The compound which does not show paramagnetism is

How can the isomeric complexes $[Co(NH_3)_6][Cr(NO_2)_6]$ and $[Cr(NH_3)_6][Co(NO_2)_6]$ be distinguished from one another?

The electronic configurations of $Cr^{2+}$,$Mn^{2+}$,$Fe^{2+}$,and $Co^{2+}$ ions are $d^4$,$d^5$,$d^6$,and $d^7$ respectively. Which of the following complexes has the minimum paramagnetic character?

Magnetic moment $2.83 \ BM$ is given by which of the following ions?
(At. nos. $Ti = 22, Cr = 24, Mn = 25, Ni = 28$)

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

List-$I$	List-$II$
$(a).$ $[Co(NH_3)_6][Cr(CN)_6]$	$(i).$ Linkage isomerism
$(b).$ $[Co(NH_3)_3(NO_2)_3]$	$(ii).$ Solvate isomerism
$(c).$ $[Cr(H_2O)_6]Cl_3$	$(iii).$ Coordination isomerism
$(d).$ $cis-[CrCl_2(ox)_2]^{3-}$	$(iv).$ Optical isomerism

Choose the correct answer from the options given below:

Which of the following is correctly matched?