Which of the following has the least ionization potential?

The first ionisation potential $(IP)$ of the elements $Na$,$Mg$,$Si$,$P$,$Cl$ and $Ar$ are $5.14$,$7.65$,$8.15$,$10.49$,$12.97$ and $15.76 \ eV$,respectively. The $IP$ (in $eV$) of $K$ is closest to

The correct order in which the first ionisation potential increases is

Which of the following is a favourable factor for cation formation?

The $IE_1$ and $IE_2$ of three elements $A$,$B$,and $C$ are given as : ( $IE$ in $kJ/mol$ )

Element	$A, B, C$
$IE_1$	$400, 550, 1150$
$IE_2$	$2650, 1070, 2090$

Identify the element which represents a nonmetal.

Which one of the following statements is incorrect in relation to ionization enthalpy?