Medium MCQ +4 / -1 PYQ · JEE Mains 2025

The extra stability of half-filled subshell is due to :

(A) Symmetrical distribution of electrons

(B) Smaller coulombic repulsion energy

(C) The presence of electrons with the same spin in non-degenerate orbitals

(D) Larger exchange energy

(E) Relatively smaller shielding of electrons by one another

Indentify the correct statements :

  1. A (B), (D) and (E) only
  2. B $(A),(B),(D)$ and (E) only Correct answer
  3. C (B), (C) and (D) only
  4. D $(A),(B)$ and (D) only

Solution

<p>The enhanced stability of a half-filled subshell is attributed to the following factors:</p> <p><p><strong>Symmetrical Distribution of Electrons</strong>: Electrons are evenly distributed across the available orbitals, leading to a balanced and stable arrangement.</p></p> <p><p><strong>Large Exchange Energy</strong>: The energy due to the exchange of electrons with parallel spins among degenerate orbitals is maximized, contributing to increased stability.</p></p> <p><p><strong>Smaller Coulombic Repulsion</strong>: The repulsion between electrons is minimized in a half-filled configuration, reducing the overall energy of the subshell.</p></p> <p><p><strong>Smaller Shielding of Electrons</strong>: In a half-filled subshell, electrons are more exposed to the nuclear charge, as there is less shielding effect from other electrons, enhancing stability.</p></p>

About this question

Subject: Chemistry · Chapter: Atomic Structure · Topic: Bohr's Model

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