In which of the following pairs, electron gain enthalpies of constituent elements are nearly the same or identical?

(A) Rb and Cs
(B) Na and K
(C) Ar and Kr
(D) I and At

Question

In which of the following pairs, electron gain enthalpies of constituent elements are nearly the same or identical?

(A) Rb and Cs
(B) Na and K
(C) Ar and Kr
(D) I and At

Canvas Classes · Accepted Answer

Strategy:
 Electron Gain Enthalpy () describes the energy change when an electron is added to a gaseous atom. Noble gases have nearly zero or slightly positive values, while elements in the same group often exhibit similar trends unless affected by size-induced repulsion.

Step 1: Evaluate Statement C (Ar and Kr)
- Both Argon () and Krypton () are noble gases with stable  configurations.
- Adding an electron requires energy to be supplied into a new higher energy shell.
- Both have nearly zero o

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