Question: is nh4i an acid or base?
Answer: NH4I, ammonium iodide, is not an acid or base; it is only a salt. But it is an acidic salt. NH4I is a salt of hydroiodic acid (HI), a strong acid, and ammonia (NH3), a weak base. An aqueous solution of such a salt is acidic (pH < 7 ) due to hydrolysis of the cation.