If $n$ is the number of unpaired electrons,then the magnetic moment $(B.M.)$ of a transition metal/ion is given by:

The electronic configurations of $Cr^{2+}, Mn^{2+}, Fe^{2+}$ and $Ni^{2+}$ ions are $3d^4, 3d^5, 3d^6$ and $3d^8$ respectively. Which of the following aqua complexes exhibits the minimum paramagnetic behavior?

The spin-only magnetic moment of an octahedral complex of $Fe^{2+}$ in the presence of a strong field ligand in $B.M.$ is $.....$

The correct order of the spin-only magnetic moments of the following complexes is
$(I) [Cr(H_2O)_6]Br_2$
$(II) Na_4[Fe(CN)_6]$
$(III) Na_3[Fe(C_2O_4)_3] (\Delta_0 > P)$
$(IV) (Et_4N)_2[CoCl_4]$

Which of the following complex compound$(s)$ is/are paramagnetic and low spin?
$(I) \, K_3[Fe(CN)_6] \quad (II) \, [Ni(CO)_4] \quad (III) \, [Cr(NH_3)_6]^{3+} \quad (IV) \, [Mn(CN)_6]^{4-}$
Choose the correct code:

In which case is a racemic mixture obtained upon mixing its mirror images ($d$ and $l$ forms) in a $1:1$ molar ratio?