$\underset{\begin{smallmatrix}
EAN=37 \\
(Less\,stable)
\end{smallmatrix}}{\mathop{[Mn{{(CO)}_{6}}]}}\,\xrightarrow{-{{e}^{-}}}\underset{\begin{smallmatrix}
EAN=36 \\
(More\,stable)
\end{smallmatrix}}{\mathop{{{[Mn{{(CO)}_{6}}]}^{+}}}}\,$
$(I)\,[Ni(CO)_4]$ $(II)\, [Mn(CN)_6]^{4-}$ $(III)\, [Cr(NH_3)_6]^{3+}$ $(IV) \,[CoF_6]^{3 -}$
તો સાચો ક્રમ શોધો
$(a)$ $\left( NH _{4}\right)_{2}\left[ Ce \left( NO _{3}\right)_{6}\right]$
$(b)$ $Gd \left( NO _{3}\right)_{3}$ અને
$(c)$ $Eu \left( NO _{3}\right)_{3}$