NEET levelSingle correct optionDifficulty 1 of 3pt118
Noble gases have positive electron gain enthalpies because
Athey have the largest atomic radii in their period
Bthey have very low nuclear charge
Cthe incoming electron must enter the next higher shell, as the valence shell is completely filled
Dthey have half-filled valence orbitals
Answer: C
In a noble gas the octet (or 1s2) is complete, so an added electron goes into a new, higher shell where it is poorly attracted and shielded. Energy must be supplied, so the value is positive.