Explanation:

* Oxidation State: The acidity of metal oxides generally increases with the oxidation state of the metal. In Mn₂O₇, manganese has an oxidation state of +7, while in MnO₂, it has an oxidation state of +4.

* Polarity: Higher oxidation states lead to more polar metal-oxygen bonds. The highly polar bonds in Mn₂O₇ make it more likely to donate protons (H⁺) and act as an acid.

* Structure: Mn₂O₇ has a more complex structure with multiple oxygen atoms bonded to the manganese atoms, which further enhances its acidic nature.

In summary:

The higher oxidation state of manganese in Mn₂O₇, along with its more polar bonds and complex structure, makes it a stronger acid compared to MnO₂.