In $K_4[Fe(CN)_6]$,the $E.A.N.$ of $Fe$ is

The effective atomic number of Iron $(Z = 26)$ in $[Fe(CN)_6]^{3-}$ is

Which of the following coordination complexes is an exception to the $EAN$ rule? (Given atomic numbers: $Pt = 78, Fe = 26, Zn = 30, Cu = 29$)

Among $V(CO)_6$,$Cr(CO)_5$,$Cu(CO)_3$,$Mn(CO)_5$,$Fe(CO)_5$,$[Co(CO)_3]^{3-}$,$[Cr(CO)_4]^{4-}$,and $Ir(CO)_3$,the total number of species isoelectronic with $Ni(CO)_4$ is. . . . . [Given atomic number : $V=23$,$Cr=24$,$Mn=25$,$Fe=26$,$Co=27$,$Ni=28$,$Cu=29$,$Ir=77$ ]

In the complex $Fe(CO)_x$,the value of $x$ is :

$[Co(NH_3)_x]Cl_3$ has $EAN$ of $Co=36$. What is the value of '$x$' $:-$