$A$ large difference between the fourth and fifth ionization energies indicates the presence of

The first four ionization energy values of an element are $191$,$578$,$872$ and $5962 \ kcal$. The number of valence electrons in the element is

The correct option for the first ionisation enthalpy (in $kJ \ mol^{-1}$) of $Li$,$Na$,$K$ and $Cs$ respectively is

Which among the following elements has the lowest value of $IE_1$?

The first ionization energy of magnesium is smaller as compared to that of elements $X$ and $Y$,but higher than that of $Z$. The elements $X$,$Y$ and $Z$,respectively,are :

Consider the following changes:
$M_{(s)} \to M_{(g)}$ ........$(1)$
$M_{(s)} \to M^{2+}_{(g)} + 2e^-$ .......$(2)$
$M_{(g)} \to M^{+}_{(g)} + e^-$ .........$(3)$
$M^{+}_{(g)} \to M^{2+}_{(g)} + e^-$ .........$(4)$
$M_{(g)} \to M^{2+}_{(g)} + 2e^-$ ..........$(5)$
The second ionization energy of $M$ could be calculated from the energy values associated with: