What does the pauli exclusion principle state?

a) electrons will be added to an atom at the lowest possible level or sublevel.

b) an orbital can contain two electrons only if all other orbitals at that sublevel are empty.

c) an orbital can contain two electrons only if all other orbitals at that sublevel contain at least one electron.

d) two electrons occupy the same orbital only if they have opposite spins.

e) an orbital can contain two electrons only if all other orbitals at that sublevel are empty.

Answer : The correct option is, (D) Two electrons occupy the same orbital only if they have opposite spins.

Explanation :

Pauli Exclusion Principle :

Pauli Exclusion Principle states that no two electrons present in an atom or a molecule can have the same set of the four quantum numbers.

It can also stated that, only two electrons may exist in the same orbital and these electrons must have opposite spin.

That means if two electrons have same value of three quantum number i.e, n, l and m but the forth quantum number that is spin quantum number is different for them.

Both the two electrons have opposing spins having value either or .

Hence, the correct option is, (D) Two electrons occupy the same orbital only if they have opposite spins.