Arrangement of electrons in atomic orbitals

• A. Pauli Exclusion Principle
• B. Hund's Rule
• C. Quantum numbers
• D. Electron configuration

Answer: (D)

Electron configuration is the direct description of how electrons occupy atomic orbitals, listing the distribution of electrons among shells and subshells in the order of increasing energy. This notation captures the actual arrangement you’re asked about, showing exactly how many electrons sit in each orbital (for example, 1s2 2s2 2p4 for oxygen). The rules like the Pauli Exclusion Principle explain why you can’t put more than two electrons with opposite spins into the same orbital, and Hund’s Rule describes how electrons fill degenerate orbitals to maximize unpaired spins before pairing. Quantum numbers are the labels used to identify each electron’s state. But the arrangement itself—the specific occupancy of each orbital—is conveyed by electron configuration, which is why it’s the best answer.