Which element has the maximum first ionization potential?

Identify the element having lowest first ionization enthalpy.

The first ionisation potential of $Na$ is $5.1 \, eV$. The value of electron gain enthalpy of $Na^{+}$ will be : ............... $eV$

Consider the following ionisation reactions:

$A_{(g)} \to A^{+}_{(g)} + e^-, \ A_1$	$B_{(g)} \to B^{+}_{(g)} + e^-, \ B_1$
$B^{+}_{(g)} \to B^{2+}_{(g)} + e^-, \ B_2$	$C_{(g)} \to C^{+}_{(g)} + e^-, \ C_1$
$C^{+}_{(g)} \to C^{2+}_{(g)} + e^-, \ C_2$	$C^{2+}_{(g)} \to C^{3+}_{(g)} + e^-, \ C_3$

If the monovalent positive ion of $A$,divalent positive ion of $B$,and trivalent positive ion of $C$ have zero electrons,then which of the following is the incorrect order of the corresponding $I.E.$?

The first ionisation energies (in $kJ \ mol^{-1}$) of four consecutive elements of the second period are given in the options. The first ionisation energy of nitrogen is

The electronic configuration with the highest ionization enthalpy is