The first ionization potentials $\left( eV \right)$ of $Be$ and $B$ respectively are:

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ The energy required to form $Mg^{2+}$ from $Mg$ is much higher than that required to produce $Mg^{+}$.
Reason $R:$ $Mg^{2+}$ is a small ion and carries more charge than $Mg^{+}$.
In the light of the above statements,choose the correct answer from the options given below:

The successive ionisation enthalpies of an element $X$ in $(kJ \ mol^{-1})$ are $1012$,$1907$,$2955$,$4955$,$6275$ and $21,260$ respectively. The element $X$ is:

Which is the correct order of the first ionization potential of $N$,$O$,and $C$?

The first four $I.E.$ values of an element are $284, 412, 656$ and $3210 \ kJ \ mol^{-1}$. The number of valence electrons in the element are

Ionization potential is lowest for