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

A: Rb & Cs
B: Na & K
C: Ar & Kr
D: I & At

Choose the correct answer:

Question

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

A: Rb & Cs
B: Na & K
C: Ar & Kr
D: I & At

Choose the correct answer:

Canvas Classes · Accepted Answer

Strategy:
 Identify pairs of elements with very similar Electron Gain Enthalpies (). Noble gases have nearly zero/positive values, and heavy elements in the same group often converge toward similar values.

Step 1: Evaluate the pairs
- Pair A (Rb & Cs): Both have very small and nearly identical  values (approx ). (Correct)
- Pair B (Na & K): Magnitude differs significantly:  () and  ().
- Pair C (Ar & Kr): Both are noble gases with completely filled shells. Their  values are very similar ( to ).

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