Question

According to Aufbau principle, the electron has a tendency to occupy that sub-shell which has:

• A. lowest energy
• B. highest energy
• C. average energy
• D. no energy

Answer 1

The correct option is A lowest energy

The Aufbau principle states that in the ground state of an atom or ion, electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels (e.g., 1s before 2s). In this way, the electrons of an atom or ion form the most stable electron configuration possible.