Question:
Identify the elements $X$ and $Y$ using the ionisation energy values given below:
Correct Option: 1
Solution:
$\mathrm{Na} \rightarrow[\mathrm{Ne}] 3 \mathrm{~s}^{1} \mathrm{IE}_{1}$ is very low but $\mathrm{IE}_{2}$ is very
high due to stable noble gas configuration of $\mathrm{Na}^{+}$
$\mathrm{Mg} \rightarrow[\mathrm{Ne}] 3 \mathrm{~s}^{2} \mathrm{IE}_{1} \& \mathrm{IE}_{2} \rightarrow$ Low
$E_{3}$ is very high.