Question

What is the electron gain enthalpy for noble gases?

(a) > 0

(b) < 0

(c) = 0

(d) It is not defined for noble gases

The question was posed to me in semester exam.

I'd like to ask this question from P-Block topic in chapter P-Block Elements of Chemistry – Class 12

Answer 1

Correct answer is (a) > 0

Explanation: Noble gases have completely filled subshells. As a result, there is no vacant room in their valence shell and hence the additional electron has to be placed in an orbital of the next higher shell. Therefore, energy has to be supplied in order to add an electron and so, the electron gain enthalpy of noble gases is positive (> 0).