Which of the following ligands will cause the smallest crystal field splitting?

Match the following complexes in List-$I$ with their electronic configurations in List-$II$.

List-$I$ (Complex)	List-$II$ (Electronic configuration of metal/ion)
$A. [Co(NH_3)_6]^{3+}$	$I. t_{2g}^5 e_g^0$
$B. [CoF_6]^{3-}$	$II. t_{2g}^6 e_g^0$
$C. [Ni(CO)_4]$	$III. t_{2g}^4 e_g^2$
$D. [Fe(CN)_6]^{3-}$	$IV. t^4 e^6$

Crystal field splitting energies for octahedral $(\Delta_0)$ and tetrahedral $(\Delta_t)$ geometries caused by the same ligands are related through the expression

The number of unpaired $d$-electrons in $[Co(H_2O)_6]^{3+}$ is $\qquad$

$A$ metal ion $M^{n+}$ having $d^6$ valence electronic configuration combines with three bidentate ligands to form a complex. Assuming crystal field splitting $(\Delta_0) >$ pairing energy,the $d$-orbital electronic configuration would be

The metal $d-$orbitals that directly face the ligands in $K_3[Co(CN)_6]$ are: