Question

explain Paulis exclusion principle

Answer 1

The Pauli exclusion principle is the quantum mechanical principle which states that two or more identical fermions (particles with half-integer spin) cannot occupy the same quantum state within a quantum system simultaneously.

Answer 2

Pauli Exclusion Principle.

The Pauli Exclusion Principle states that, in an atom or molecule, no two electrons can have the same four electronic quantum numbers.

As an orbital can contain a maximum of only two electrons, the two electrons must have opposing spins.