$(I)$ $\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right] \mathrm{Br}_{2}$

$(II)$ $ \mathrm{Na}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]$

$(III)$ $\mathrm{Na}_{3}\left[\mathrm{Fe}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]\left(\Delta_{0}>\mathrm{P}\right)$

$(IV)$ $\left(\mathrm{Et}_{4} \mathrm{N}\right)_{2}\left[\mathrm{CoCl}_{4}\right]$

$(1) $ $[Ag(NH_3)_2]^{+}$ - રેખીય

$ (2) $ $[MnCl^4]^{2-}$ - ચતુષ્ફલકીય

$(3) $ $[Cu(NH_3)_4]^{2+}$ - ચોરસ સમતલ 

$(4) $ $[Ni(CN)_4]^{2-}$ - ચોરસ સમતલ

(પ. ક્ર.: $Sc = 21 , Ti = 22, V = 23, Zn = 30$)