Question

why ne has positive value for electron gain enthalpy

Answer 1

Answer:

Neon has a complete valence shell hence there will be a lot of repulsion when you try to add an electron in its valence shell. This means you are providing energy which the reaction endothermic.

According to sign convention values depicting endothermic reaction have positive sign.

Hence Ne has positive electron gain enthalpy.

Hope it helps...........