Answer: Pauli exclusion principle.
- A Hund's rule
- B Aufbau principle
- C Pauli exclusion principle
- D Heisenberg principle
Correct answer: C. Pauli exclusion principle
Explanation: The Pauli exclusion principle states that no two electrons in an atom can have identical four quantum numbers.
Bohr's model: electrons occupy fixed circular shells (K, L, M) around the nucleus, with each shell holding up to 2n2 electrons.
Concept context
Explore how electrons are arranged inside an atom. Covers Bohr's model, quantum numbers, Heisenberg's uncertainty principle, shapes of s, p, d orbitals, and electronic configuration rules.