Question

Positive Electron gain enthalpy of noble gases decreases in the order:
(A)He > Ne >Ar> Kr >Xe> Rn
(B)He > Ne >Ar = Kr >Xe> Rn
(C) Ne >Ar = Kr >Xe> Rn > He
(D)Ne >Ar = Kr >Xe< Rn > He​

Answer 1

Answer:

The positive Electron Gain Enthalpy for noble gases decreases in the order of Ne $>$ Ar $=$ Kr $>$ Xe $>$ Rn $>$ He· (option c)

Explanation:

Electron gain enthalpy is defined as the amount of energy released when an electron is added to an isolated gaseous atom·

We know that noble gases are the 18th group element and are reluctant to gain or lose their electrons because of having filled outer electronic shells· Usually, the EGE values are negative, but noble gases have a positive EGE value·

As we go down the group, the value of  EGE is increasing· This is because, as the size of the atom increases, the distance between the nucleus and the outermost shell increases· So, the nuclear charge increases, and thus the value of positive EGE decreases·

Because of the higher tendency to accept electrons, He shows an exception among the group·

Hence the decreasing order follows Ne $>$ Ar $=$ Kr $>$ Xe $>$ Rn $>$ He·