The one that is not expected to show isomerism is:

What is the magnetic moment of $[FeF_6]^{3-}$ (in $BM$)?

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

The metal ion whose electronic configuration is not affected by the nature of the ligand and which gives a violet colour in non-luminous flame under hot condition in borax bead test is

The species with spin only magnetic moment of $\sqrt{24} \, BM$ is

Which one of the following complexes will exhibit the least paramagnetic behaviour?
[Atomic number: $Cr=24, Mn=25, Fe=26, Co=27$]