Step 1: Explanation of \( E^0 \) Value - The electrode potential (\( E^0 \)) depends on: - Atomization enthalpy (\( \Delta H^0_{\text{atom}} \)): The energy required to convert solid Cu to Cu\(^{2+}\) is high. - Hydration enthalpy (\( \Delta H^0_{\text{hydr}} \)): Cu\(^{2+}\) has low hydration energy, making it less stable in aqueous solution.
Step 2: Effect on \( E^0 \) Value - Due to low hydration enthalpy, the reduction of Cu\(^{2+}\) to Cu is not highly favored. - Hence, Cu\(^{2+}/\)Cu has a positive \( E^0 \) value of \( +0.34 \) V, indicating that Cu is less reactive than expected.
A transition metal (M) among Mn, Cr, Co and Fe has the highest standard electrode potential \( (M^{3+} / M^{2+}) \). It forms a metal complex of the type \( [M(CN)_6]^{4-} \). The number of electrons present in the \( e_g \) orbital of the complex is ________.

