Why is third ionisation enthalpy of manganese exceptionally high ?

Why is the third ionisation energy of manganese exceptionally high ?

Give reasons for the following observations : The third ionisation enthalpy of manganese (Z = 25) is exceptionally high

How would you account for the following ? The third ionization enthalpy of manganese (Z = 25) is exceptionally high.

Give reasons: Third ionisation enthalpy of manganese is unusually high.

Why third ionisation enthalpy of Mn is very high?

Give Reason. Second ionisation enthalpy of copper is exceptionally high.

Why is the third ionization enthalpy of manganese (At. no.=25) unexpectedly high ?

Why is the ionisation enthalpy of magnesium higher than that of potassium ?