This is in contrast with the variability of oxidation states of non
transition elements where oxidation states normally differ by a unit
of two An interesting feature in the variability of oxidation states of the d–
block elements is noticed among the groups (groups 4 through 10) Although in the p–block the lower oxidation states are favoured by the
heavier members (due to inert pair effect), the opposite is true in the
groups of d-block For example, in group 6, Mo(VI) and W(VI) are
found to be more stable than Cr(VI)