For which of the following coordination complexes will the value of $\Delta_0$ be the maximum?

Based on Crystal Field Theory,show the energy level splitting and determine the $d$-electron configuration and magnetic moment for the central metal atom/ion in the following complexes: $[CoF_6]^{3-}$,$[Co(H_2O)_6]^{2+}$,$[Co(CN)_6]^{3-}$.

Correct increasing order for the wavelength of absorption in the visible region for the complexes of $Co^{3+}$ is :

The Crystal Field Stabilization Energy $(CFSE)$ and magnetic moment (spin-only) of an octahedral aqua complex of a metal ion $(M^{2+})$ are $-0.8\, \Delta_{0}$ and $3.87\, BM$,respectively. Identify $(M^{2+})$:

Match List-$I$ with List-$II$.

List-$I$ (Coordination entity)	List-$II$ (Wavelength of light absorbed in $nm$)
$A$. $[CoCl(NH_3)_5]^{2+}$	$I$. $310$
$B$. $[Co(NH_3)_6]^{3+}$	$II$. $475$
$C$. $[Co(CN)_6]^{3-}$	$III$. $535$
$D$. $[Cu(H_2O)_4]^{2+}$	$IV$. $600$

Choose the correct answer from the options given below:

The number of complexes from the following with no electrons in the $t_{2g}$ orbital is: $TiCl_4, [MnO_4]^{-}, [FeO_4]^{2-}, [FeCl_4]^{-}, [CoCl_4]^{2-}$