What is effective atomic number of $\mathrm{Pt} \operatorname{in}\left[\mathrm{Pt}\left(\mathrm{NH}_3\right)_4\right]^{2+}$ ? (Given atomic number of $\mathrm{Pt}=78$ )

$$ \left[\mathrm{Pt}\left(\mathrm{NH}_3\right)_4\right]^{2+} \Rightarrow \mathrm{Pt}^{2+} $$ \begin{array}{|l|l|l|l|l|l|} \hline Complex & Metal & \begin{array}{l}\text { Atomic } \\ \text { number of } \\ \text { metal Z }\end{array} & \begin{array}{l}\text { Number of } \\ \text { electrons lost } \\ \text { by metal X }\end{array} & \begin{array}{l}\text { Number of } \\ \text { electrons } \\ \text { from } \\ \text { ligands Y }\end{array} & EAN = Z-X + Y \\ \hline\left[\mathrm{Pt}\left(\mathrm{NH}_3\right)_4\right]^{2+} & \mathrm{Pt} & 78 & 2 & 4 \times 2=8 & 78-2+8=84 \\ \hline \end{array}