In a $d^4$ low spin complex,what will be the magnetic moment $(\mu)$ in $B.M.$ if the coordination number is $6$?

In $Cr^{2+}, Mn^{2+}, Fe^{2+},$ and $Ni^{2+}$,the number of electrons in the $3d$ orbital are $3d^4, 3d^5, 3d^6,$ and $3d^8$ respectively. Which of the following aqueous complexes will have the lowest magnetic moment?

Match the complex ion (in List-$I$) with the number of unpaired electrons (in List-$II$):

List-$I$	List-$II$
$A$. $[Fe(H_2O)_6]^{2+}$	$P$. $0$
$B$. $[Fe(H_2O)_6]^{3+}$	$Q$. $1$
$C$. $[Fe(CN)_6]^{4-}$	$R$. $2$
$D$. $[Fe(CN)_6]^{3-}$	$S$. $4$
$E$. $[Ni(H_2O)_4]^{2+}$	$T$. $5$

Which of the following compounds shows optical isomerism?

Which of the following complexes is colorless?

The correct order of magnetic moments (spin-only values in $B.M.$) among the following is:
(Atomic numbers: $Mn = 25, Fe = 26, Co = 27$)