Arrange the ligands $NH_3, en, Cl^-,$ and $CO$ in the increasing order of their field strength (spectrochemical series).

The molar ionic conductances of the octahedral complexes are in the order of:
$(1) PtCl_4 \cdot 5NH_3$
$(2) PtCl_4 \cdot 4NH_3$
$(3) PtCl_4 \cdot 3NH_3$
$(4) PtCl_4 \cdot 2NH_3$

Which complex is most stable? Where $k_d =$ Dissociation constant.

Identify the correct statements from the following:
$A$. $[Fe(C_2O_4)_3]^{3-}$ is the most stable complex among $[Fe(OH)_6]^{3-}$, $[Fe(C_2O_4)_3]^{3-}$ and $[Fe(SCN)_6]^{3-}$.
$B$. The stability of $[Cu(NH_3)_4]^{2+}$ is greater than that of $[Cu(en)_2]^{2+}$.
$C$. The hybridization of $Fe$ in $K_4[Fe(CN)_6]$ is $d^2sp^3$.
$D$. $[Fe(NO_2)_3Cl_3]^{3-}$ exhibits linkage isomerism.
$E$. $NO_2^-$ and $SCN^-$ ligands are $NOT$ ambidentate ligands.
Choose the correct answer from the options given below:

$X$ is the number of electrons in $t_{2g}$ orbitals of the most stable complex ion among $[Fe(NH_3)_6]^{3+}$,$[Fe(Cl)_6]^{3-}$,$[Fe(C_2O_4)_3]^{3-}$ and $[Fe(H_2O)_6]^{3+}$. The nature of the oxide of vanadium of the type $V_2O_X$ is:

The purple color of $KMnO_4$ is due to which of the following?