Question

The rule which describes the electron distribution in degenerate orbitals of an atom is

• A. Aufbau principle
• B. Pauli exclusion principle
• C. Hund's rule
• D. Planck's theory

Answer 1

The Correct Option is C

Hund's rule states that electrons occupy degenerate orbitals (orbitals with the same energy) singly first, with parallel spins, before pairing begins.  
This minimizes electron repulsion and stabilizes the atom.  
Hence, Hund's rule governs the distribution of electrons in degenerate orbitals such as the \( p \), \( d \), or \( f \) subshells.

- Aufbau principle explains the order of filling orbitals.  
- Pauli exclusion principle states that no two electrons in the same atom can have all four quantum numbers identical.  
- Planck’s theory deals with quantization of energy, not electron configurations.

The correct option is (C): Hund's rule