GKFix MCQ Question

Why is the ionization enthalpy of Fe2+ lower than that of Mn2+?

• A. Fe2+ has a d6 configuration which gains stability from losing an electron, unlike the stable d5 configuration of Mn2+
• B. Mn2+ has a d5 configuration which gains stability from losing an electron, unlike the stable d6 configuration of Fe2+
• C. Fe2+ has a smaller ionic radius
• D. Mn2+ has a larger ionic radius