The highest value for Zn is attributed to the removal of an electron from the stable d¹⁰ configuration of Zn²⁺, emphasizing the significance of achieving a fully filled d orbital for stability.

The comparatively high value for Mn signifies the stability of Mn²⁺(d⁵), while the comparatively low value for Fe highlights the extra stability associated with Fe³⁺(d⁵), showcasing the influence of electron configurations on oxidation state stability.

Cr and Cu show high second ionization enthalpies due to the removal of electrons from d orbitals, resulting in d⁵ and d¹⁰ configurations in M²⁺ ions, influencing their stability.

Fe²⁺ has a d⁶ configuration, while Mn²⁺ has a 3d⁵ configuration. The absence of exchange energy loss in the d⁶ configuration of Fe²⁺ results in lower ionization enthalpy compared to Mn²⁺, indicating that the third ionization enthalpy of Fe is ...

Mn⁺ has a 3d⁵4s¹ configuration, while Cr⁺ has a d⁵ configuration. The absence of loss of exchange energy in the d⁶ configuration of Mn⁺ leads to lower ionization enthalpy compared to Cr⁺, showcasing the influence of exchange energy on stability ...