First three ionisation energies (in $\mathrm{kJ} / \mathrm{mol}$) of three representative elements are given…

First three ionisation energies (in $\mathrm{kJ} / \mathrm{mol}$) of three representative elements are given below:
$\begin{array}{|l|l|l|l|} \hline \text { Element } & \text { IE }_{1} & \text { IE }_{2} & \text { IE }_{3} \\ \hline \text { P } & 495.8 & 4562 & 6910 \\ \hline \text { Q } & 737.7 & 1451 & 7733 \\ \hline \text { R } & 577.5 & 1817 & 2745 \\ \hline \end{array}$ Then incorrect option is :
  1. $\mathrm{Q}:$ Alkaline earth metal
  2. $\mathrm{P}:$ Alkali metals
  3. $\mathrm{R}:$ p-block element
  4. They belong to same period

Solution

$\mathrm{R}$ is $p$ -block element, because difference between $\mathrm{IE}_{2}$ and $\mathrm{IE}_{3}$ is not very high as compared to between $\mathrm{IE}_{1}$ and $\mathrm{IE}_{2}$; hence stable oxidation state of $\mathrm{R}$ will be higher than $+2$.

Asked in: JEE-TOPICTESTS-CHEMISTRY

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