Ionisation enthalpy `(Delta_(t)H_(l) "in" kJ mol^(-1))` for the elements of group-13 follows the order

Ionisation enthalpy (Delta_(i)"H kJ mol"^(-1)) for the elements of group 13 follows the order.

Ionisation enthalpy (Delta_(i)"H kJ mol"^(-1)) for the elements of group 13 follows the order.

The first ionisation enthalpy values (in kJ mol^(-1) ) of group 13 elements are How would you explain this deviation from the general , trend?

The first (Delta_(i)H_(1)) and second (Delta_(i)H_(2)) ionization enthalpies ("in kJ mol"^(-1)) and the electron gain enthalpy (Delta_(eg)H)("in kJ mol"^(-1)) of the elements I, II, III, IV and V are given below the least reactive non - metal and the most reactive metal of these are respectively