What kind of reaction occurs when you mix aqueous solutions of barium sulfide and sulfuric acid?

A smelly one

##BaS(aq) + H_2SO_4(aq) rarr BaSO_4(s)darr + H_2S(aq)##

This is (i) an acid base reaction, and (ii) a precipitation reaction as barium sulfate is pretty insoluble stuff (##K_(sp)=1.08xx10^-9## at ##298*K##).