Oxygen cannot exhibit tetra valency and hexa valency like Sulphur. This is because

The atomic number of Oxygen is Z = 8. So the electronic configuration of Oxygen is

$1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}_{\mathrm{x}}^{2}2{\mathrm{p}}_{\mathrm{y}}^{1}2{\mathrm{p}}_{\mathrm{z}}^1$

There is no empty ‘d’ orbitals for Oxygen atom in its valence shell 2 nd shell (Lack of valence ‘d’ orbitals). Hence, there is no possibility to promote electrons into d-subshell in case of Oxygen. Therefore, Oxygen cannot show tetra valency and hexa valency as like as Sulphur.