What type of oxides are formed when non-metals combine with oxygen?

When non-metals combine with oxygen, the oxides of non-metals are formed. For example, S + O₂ → SO₂
Here sulphur is a non-metal which combines with oxygen gas to form sulphur dioxide. When this sulphur dioxide is dissolved in water sulphurous acid is formed.
SO₂ + H₂O → H₂SO₃
This sulphurous acid can turn blue litmus paper red. This indicates that oxides of non-metals are acidic in nature.