Total number of relatively more stable isomer$(s)$ possible for octahedral complex $[Cu(en)_2(SCN)_2]$ will be $.........$

Consider the following complex ions,$P$,$Q$ and $R$.
$P = [FeF_6]^{3-}$,$Q = [V(H_2O)_6]^{2+}$ and $R = [Fe(H_2O)_6]^{2+}$.
The correct order of the complex ions,according to their spin-only magnetic moment values (in $B.M.$) is

Which of the following complexes exhibits both geometrical and optical isomerism? $(en = \text{ethylenediamine})$

In $[Cr(C_2O_4)_3]^{3-}$,the isomerism shown is :-

There are four complexes of $Ni$. Select the complex(es) which will be attracted by a magnetic field:
$(I) \ [Ni(CN)_4]^{2-}, \ (II) \ [NiCl_4]^{2-}, \ (III) \ [Ni(CO)_4]$
$(IV) \ [Ni(H_2O)_6]^{2+}$

Among the following options,select the option in which each complex in Set-$I$ shows geometrical isomerism and the two complexes in Set-$II$ are ionization isomers of each other.
$[en = H_2N-CH_2-CH_2-NH_2]$