WAEC Chemistry 2020 Objective — Question 39

Question 39 of 50 from the West African Examinations Council (WAEC) Chemistry 2020 Objective paper, with the correct answer and a full explanation.

"Electrons always occupy the lowest empty energy level" is a statement of

A. Aufbau PrincipleCorrect
B. Hund's rule
C. Pauli Exclusion Principle
D. Periodic law

Explanation

This is a statement of the Aufbau principle. Hund's rule of maximum multiplicity states that electrons go into degenerate orbitals before pairing begins. Pauli Exclusion Principle states that no two electrons can have the same values for all the quantum numbers. Periodic law states that the properties of elements are periodic functions of their atomic numbers.

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