Question

$E_{M{n}^{3+}/M{n}^{2+}}^0$ is highly positive than that of $E_{C{r}^{3+}/C{r}^{2+}}^0\text{or}{E}_{F{e}^{3+}/F{e}^{2+}}^0$ because

• A. $M{n}^{2+}\left(d^5\right)$ can be easily oxidised to $M{n}^{3+}\left(d^4\right)$ due to low ionisation enthalpy
• B. Third ionisation enthalpy of Mn is much larger due to stable half filled $d^5$ electronic configuration of $M{n}^{2+}$
• C. $M{n}^{3+}$ is more stable than $M{n}^{2+}$ due to higher oxidation state.
• D. second ionisation enthalpy of Mn is higher than third ionisation enthalpy.

Answer 1

The correct option is B Third ionisation enthalpy of Mn is much larger due to stable half filled $d^5$ electronic configuration of $M{n}^{2+}$

The third ionisation energy of Mn required to change $M{n}^{2+}\left(d^5\right)\text{to}M{n}^{3+}\left(d^4\right)$ is much larger due to stable half-filled $d^5$ electronic configuration.