In $[Ni(NH_3)_4]SO_4$,the $E.A.N.$ of $Ni$ is

The atomic number of cobalt is $27$. The $EAN$ of cobalt in $Na_{3}[Co(NO_{2})_{4} Cl_{2}]$ is

Which complex follows the Sidgwick $EAN$ rule (where atomic number of $M = 24$)?

$a$. Answer the following questions:
$i$. Which element of the first transition series has the highest second ionisation enthalpy?
$ii$. Which element of the first transition series has the highest third ionisation enthalpy?
$iii$. Which element of the first transition series has the lowest enthalpy of atomisation?
$b$. Identify the metal and justify your answer:
$i$. Carbonyl $M(CO)_5$
$ii$. $MO_3F$

What is the $EAN$ (Effective Atomic Number) of the metal ion in the hexacyanoferrate$(II)$ ion?

What is the effective atomic number $(EAN)$ of $Pt$ in $[Pt(NH_3)_4]^{2+}$? (Given atomic number of $Pt = 78$)