Is sulphur dioxide an acid base or neutral?

Sulphur dioxide is an ACIDIC gas.

When it is dissolved in water it form the acid ; SULPHUROUS ACID ( H2SO3).

Note the spelling and the number of oxygen atoms in combination.

NB The oxides of non-metallic elements on the right hand side of the Periodic Table all produce acids. e.g. Carbon Dioxide/Carbonic Acid . Nitrogen dioxide/Nitric Acid, Phosphorus oxides/phossphoric acid. etc.,

NNNB The metal oxides on the left hand side of the Periodic Table produce bases/alkalis.