Question

The maximum number of orbitals which can be identified with $n = 4$ and $m_l = 0$ is ______

Answer 1

For $n = 4$, the possible subshells are :
4s (1 orbital)
4p (3 orbitals)
4d (5 orbitals)
4f (7 orbitals)
Among these, only one orbital from each subshell can have a magnetic quantum number $m_l = 0$. Therefore, there is one such orbital from 4s, one from 4p, one from 4d, and one from 4f.
Thus, the total number of orbitals with $n = 4$ and $m_l = 0$ is 4.