The second ionisation potential of $Li, Be,$ and $B$ follows the order:

The successive ionization energies of an element $(A)$ are given as $IE_1 = 20 \ eV, IE_2 = 45 \ eV, IE_3 = 150 \ eV, IE_4 = 900 \ eV, IE_5 = 1800 \ eV$. What is the formula of the halide of $(A)$?

The first ionisation enthalpies for three elements are $1314$,$1680$ and $2080 \, kJ \, mol^{-1}$,respectively. The correct sequence of the elements is

Triad-$I$ $[N^{3-}, O^{2-}, Na^{+}]$
Triad-$II$ $[N^{+}, C^{+}, O^{+}]$
Choose the species of lowest $IP$ from triad-$I$ and highest $IP$ from triad-$II$ respectively.

Which of the following represents the correct order of increasing first ionization enthalpy for $Ca, Ba, S, Se$ and $Ar$?

The successive ionisation energy values for an element $X$ are given below. Element $X$ belongs to which group?
$1^{st} \text{ IE} = 410 \ kJ \ mol^{-1}$
$2^{nd} \text{ IE} = 820 \ kJ \ mol^{-1}$
$3^{rd} \text{ IE} = 1100 \ kJ \ mol^{-1}$
$4^{th} \text{ IE} = 1500 \ kJ \ mol^{-1}$
$5^{th} \text{ IE} = 3200 \ kJ \ mol^{-1}$