The clement. having highest electron gain enthalpy (with sign) among group 18 elements are :

 Electron gain enthalpy in (kJ mol−1) of the given element is,

$\begin{array}{l}\mathrm{He}\to 48\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\mathrm{Ne}\to 116\\ \mathrm{Ar}\to 96\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em} \mathrm{Kr}\to 96\\ \mathrm{Xe}\to 77\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\mathrm{Rn}\to 68\end{array}$

Here neon has the highest value of electron gain enthalpy