For elements $B$,$C$,$N$,$Li$,$Be$,$O$ and $F$,the correct order of first ionization enthalpy is:

Consider the following ionization enthalpies of two elements $A$ and $B$.

Element	Ionization enthalpy $(kJ \ mol^{-1})$ $(1^{st}, 2^{nd}, 3^{rd})$
$A$	$899, 1757, 14847$
$B$	$737, 1450, 7731$

Which of the following statements is correct?

From the following elements,which of them has the highest second ionisation potential?

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 $(A)$?

Which of the following isoelectronic ions has the lowest ionization energy?

The first ionization enthalpies of $Li$,$Be$,and $C$ are $520$,$899$,and $1086 \ kJ \ mol^{-1}$ respectively. Which of the values $800$ or $900 \ kJ \ mol^{-1}$ is more likely for the first ionization enthalpy of $B$? Why?