The atomic numbers of $Cr$ and $Fe$ are $24$ and $26$ respectively. Which of the following is paramagnetic in terms of electron spin?

$A$ metal complex with a formula $MCl_4 \cdot 3NH_3$ is involved in $sp^3d^2$ hybridisation. It upon reaction with excess of $AgNO_3$ solution gives '$x$' moles of $AgCl$. Consider '$x$' is equal to the number of lone pairs of electron present in the central atom of $BrF_5$. Then the number of geometrical isomers exhibited by the complex is $............$

The number of possible geometric isomers for a square planar complex $[Mabcd]$ is ............. ($M =$ central metal,$a, b, c, d =$ monodentate ligands).

In the coordination complex $[CoF_6]^{3-}$,the number of unpaired electrons is equal to ......

Total number of geometrical isomers possible for the complexes $[NiCl_4]^{2-}$,$[CoCl_2(NH_3)_4]^{+}$,$[Co(NH_3)_3(NO_2)_3]$ and $[Co(NH_3)_5Cl]^{2+}$ is

The metal complex that is diamagnetic is (Atomic number: $Fe = 26, Cu = 29$)