Write the important conditions required for the linear combination of atomic orbitals to form molecular orbitals.

(N/A) The following conditions must be satisfied by atomic orbitals to form molecular orbitals:
$(a)$ The combining atomic orbitals must have the same or nearly the same energy. This means that in a homonuclear molecule,the $1s$ atomic orbital of an atom can combine with the $1s$ atomic orbital of another atom,and not with the $2s$ orbital.
$(b)$ The combining atomic orbitals must have proper orientations to ensure that the overlap is maximum.
$(c)$ The extent of overlapping should be large.