JEE Main 2022 — Classification of Elements and Periodicity in Properties Question with Solution

Electron gain enthalpy values of the elements are given below in $\mathrm{kJ}/\mathrm{mol}$,

$\begin{array}{cccc}\mathrm{F}& \mathrm{Cl}& \text{ Te }& \text{ Po }\\ -333& -349& -190& -174.\end{array}$

Down the group electron affinity decreases. The size of fluorine atom is small. The addition of electron to small fluorine atom results in electron-electron repulsions. Hence, fluorine has less electron affinity than chlorine.

Hence, the correct order is 

$\mathrm{Cl}>\mathrm{F}>{\mathrm{Te}}_{}>\mathrm{PO}$