Reducing property of dioxides decreases from `SO_2` to `TeO_2`. Why ?

Explanation

`SO_2` undergoes oxidation to `SO_4^(2 -)` and thus is reducing.
`overset(4+) SO_2 rarr underset("More stable state") (overset(6+) SO_4^(2-) + 2e^(Ө)`
(ii) `TeO_2` undergoes reduction to `TeO` and thus is oxidising or less reducting. This is due to the inert pair effect. Lower `O.S` is more stable down the group.
`2e^(Ө) + overset (4+) (TeO_2) rarr overset (2+) (TeO)`.