Inert gases have positive electron gain enthalpy. Its correct order is

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Noble gases have positive (endothermic) electron gain enthalpies because their outermost shells are completely filled — adding an electron would require placing it in a higher energy orbital.

The electron gain enthalpy becomes more positive (less favourable) as we go up the group (smaller atoms, higher nuclear charge relative to size, more stable configuration):

- He: Smallest, most stable → most positive EGE
- Ne: Very stable
- Kr: Less stable than Ne
- Xe: Least stable → least positive EGE

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