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.
The total number of molecular orbitals formed from 2s and 2p atomic orbitals of a diatomic molecule is _________.