Mention the conditions for combination of atomic orbitals.

Explanation

The conditions for the combination of atomic orbitals are
1) The combining atomic orbitals should have comparable energy. 1s orbital can combine with another 1 s orbital but not with 2s orbital. 2) The combining atomic orbitals should have the same symmetry about the moecular axis. For example : 2p orbital can combine with 2s orbital or another `2p_(z)` orbital but not with `2p_(x)or2p_(y)`.
2s cannot combine with `2p_(x)or2p_(y)`
3) The combining atomic orbitals must overlap to the maximum extent.