According to VBT any covalent bond will be formed by overlapping of atomic orbitals of bonded atoms provided atomic orbitals must be half-filled and electrons be in opposite spin. According to type of overlapping covalent bonds can be classified as (a) σ -bond (b) π -bond (c) δ -bond:
The combination of orbital that can not produce non-bonding molecular orbital is (inter-nuclear axis is z -axis):
a. py+dx2−y2
b. pz+dyz
c. s+dxz
d. dxy+dxy