where $\varepsilon_{\mathrm{a}} \Rightarrow$ absorbed energy (splitting energy)
$\lambda_{\mathrm{a}} \Rightarrow$ absorbed wavelength
Presence of $\mathrm{SFL} \Rightarrow \varepsilon_{\mathrm{a}}(\uparrow) \lambda_{\mathrm{a}}(\downarrow)$
$\mathrm{H}_{2} \mathrm{O}<\mathrm{NH}_{3}<$ en ligand strength $\uparrow$ splitting energy $\uparrow$ so absorbed $\lambda \downarrow$
$(A)$ $\mathrm{Ni}(\mathrm{CO})_{4}$
$(B)$ $\left[\mathrm{Ni}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right] \mathrm{Cl}_{2}$
$(C)$ $\mathrm{Na}_{2}\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]$
$(D)$ $\mathrm{PdCl}_{2}\left(\mathrm{PPh}_{3}\right)_{2}$
(પ.ક્ર. : $Fe=26, Co= 27, Ni =28, Pt= 78$)