Question

The incorrect relationship in the following pairs in relation to ionisation enthalpies is:

• A. \( \text{Mn}^{2+}<\text{Cr}^{3+} \)
• B. \( \text{Mn}^{2+}<\text{Mn}^{3+} \)
• C. \( \text{Fe}^{2+}<\text{Fe}^{3+} \)
• D. \( \text{Fe}^{2+}<\text{Fe}^{3+} \)

Hint:

Ionisation enthalpy depends on the electron configuration, stability, and half-filled stability of orbitals.

Answer 1

The Correct Option is D

The incorrect relationship is between \( \text{Fe}^{2+} \) and \( \text{Fe}^{3+} \). According to ionisation enthalpies, \( \text{Mn}^{2+} \) has more ionisation energy than \( \text{Fe}^{2+} \), and \( \text{Mn}^{3+} \) has more ionisation energy than \( \text{Fe}^{3+} \).
Thus, the correct answer is (4).