Question

Which of the following explains the sequence of filling of subshells of an atom?

• A. Hund's rule
• B. Pauli's exclusion principle
• C. Aufbau principle
• D. All of these.

Answer 1

The correct option is C Aufbau principle

According to Aufbau principle, in the ground state of an atom or ion, electrons first occupy the lowest energy orbital available to them and enter into higher energy orbitals only after the lower energy orbitals are filled.

Pauli's exclusion principle states that in an atom, no two electrons can have the same set of four quantum numbers.

Hund's rule states that every orbital in a subshell is singly occupied with one electron before pairing up of electrons can take place.

Therefore, the given statement is explained by the Aufbau principle as subshell order is decided by aufbau principle.