Which of the following spin paramagnetic complexes shows both geometrical and optical isomerism?

The complex,$[Pt(Py)(NH_3)BrCl]$,will have how many geometrical isomers?

The magnetic moment (spin only) of $[NiCl_{4}]^{2-}$ is ....... $B.M.$

The magnetic moments of the following,arranged in decreasing order,will be:-
$(i)$ $Co^{3+}$ (Octahedral complex with a strong field ligand)
$(ii)$ $Co^{3+}$ (Octahedral complex with a weak field ligand like $F^{-}$)
$(iii)$ $Co^{2+}$ (Tetrahedral complex)
$(iv)$ $Co^{2+}$ (Square planar complex)

The number of geometrical isomers of $[CrCl_2(en)(NH_3)_2]$,where $en = \text{ethylenediamine}$,is

The spin-only magnetic moment of $Ni^{2+}$ in an aqueous solution in Bohr magneton $(\mu_B)$ is .......