Match the following

	List -I (complex)		List -I (electronic configuration of metal/ ion)
A	${\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_6\right]}^{3+}$	I	${\mathrm{t}}_{2g}^5{\mathrm{e}}_g^0$
B	${\left[{\mathrm{CoF}}_6\right]}^{3-}$	II	${\mathrm{t}}_{2g}^6{\mathrm{e}}_g^0$
C	$\left[\mathrm{Ni}\right(\mathrm{CO}{)}_4]$	III	${\mathrm{t}}_{2g}^4{\mathrm{e}}_g^2$
D	${\left[\mathrm{Fe}\right(\mathrm{CN}{)}_6]}^{3-}$	IV	${\mathrm{t}}_2^4{\mathrm{e}}^6$

The correct answer is

${\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_6\right]}^{3+}$= Co is in +3 oxidation state and NH₃ is a strong ligand. Its electronic configuration is ${\mathrm{t}}_{2g}^6{\mathrm{e}}_g^0$

${\left[{\mathrm{CoF}}_6\right]}^{3-}$= Co is in +3 oxidation state and F is a weak ligand. Its electronic configuration is ${\mathrm{t}}_{2g}^4{\mathrm{e}}_g^2$

$\left[\mathrm{Ni}\right(\mathrm{CO}{)}_4]$ = Nickel is in 0 oxidation state and Co is a strong ligand. Its electronic configuration is ${\mathrm{t}}_2^4{\mathrm{e}}^6$

${\left[\mathrm{Fe}\right(\mathrm{CN}{)}_6]}^{3-}$= Fe is in +3 oxidation state and CN^- is a strong ligand. Its electronic configuration is ${\mathrm{t}}_{2g}^5{\mathrm{e}}_g^0$