Which factors influence the value of ionization enthalpy?

If energy absorbed for conversion of $M_{(g)}$ into $M_{(g)}^{+}$ for $Li, Be, B, C$ and $N$ is $a, b, c, d$ and $e$ (in $k\,cal/mol$) respectively,then the correct order will be:

In each period,the alkali metals...

The correct order of first ionization enthalpy values of the following elements is:
$A. O$,$B. N$,$C. Be$,$D. F$,$E. B$
Choose the correct answer from the options given below:

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 ionization potential of $Na, Mg, Al$ and $Si$ are in the order: