1. The problem statement, all variables and given/known data The question asks me to use the modified Arrhenius theory of acids to classify the following as strong or weak acids, HNO3(aq), HI(aq) and HF(aq). 2. Relevant equations But the book only says that the modified Arrhenius theory for acids is, "an Arrhenius acid reacts with water to produce H3O+ (aq) in aqueous solution". 3. The attempt at a solution There just doesn't seem to be enough information for me to know what percent of the solution is H3O+ ions.