GKFix MCQ Question

Why do the third ionization enthalpies of Cr and Cu have exceptionally high values?

• A. Because Cr and Cu are metals.
• B. Because Cr and Cu have high atomic numbers.
• C. Because removing the third electron disrupts the exceptionally stable half-filled (Cr: 3d^5) or fully-filled (Cu: 3d^10) 3d configurations.
• D. Because Cr and Cu are located at the end of the series.