Concept:The second ionization energy spikes massively when the removal of the second electron requires breaking into a highly stable, completely filled noble gas core.
Formula:$$ \text{K}^+ \text{ configuration: } 1s^2, 2s^2, 2p^6, 3s^2, 3p^6 \text{ (Argon core)} $$
Solution:- Potassium (K) is a Group 1 alkali metal. It easily loses its single valence electron to form a \( \text{K}^+ \) ion.
- This \( \text{K}^+ \) ion is isoelectronic with Argon, possessing a perfectly stable octet.
- Removing a second electron requires disrupting this incredibly stable core, demanding a massive amount of energy compared to elements with multiple valence electrons.
Why other options are incorrect:- Option B, Option C, Option D: Calcium, Chlorine, and Bismuth have multiple electrons in their valence shell. Their second ionization does not involve breaking a noble gas core.
Quality & Fidelity Assurance:
Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.