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

Extra Stability of Half-Filled Subshell | JEE Mains PYQ | Structure of Atom

(A) Symmetrical distribution of electrons

(B) Smaller coulombic repulsion energy

(D) Larger exchange energy

(E) Relatively smaller shielding of electrons by one another

Identify the correct statements :

A. (B), (D) and (E) only

B. (A), (B), (D) and (E) only

C. (B), (C) and (D) only

D. (A), (B) and (D) only

Explanation

Step 1: Symmetrical distribution

Half-filled subshells have symmetrical distribution of electrons, which increases stability. So, statement (A) is correct.

Step 2: Coulombic repulsion

Electrons occupy different orbitals with parallel spins, reducing electron-electron repulsion. Hence, statement (B) is correct.

Step 3: Exchange energy

Maximum number of possible exchanges occur in half-filled subshells, leading to larger exchange energy. So, statement (D) is correct.

Step 4: Shielding effect

Due to parallel spins and uniform distribution, shielding between electrons is relatively smaller. Thus, statement (E) is correct.

Step 5: Check incorrect statement

Statement (C) is incorrect because half-filled stability involves degenerate orbitals, not non-degenerate ones.

Correct Answer = (A), (B), (D) and (E) only

Previous Year Questions – Structure of Atom