Multiple choice general knowledge science & technology Which one of below is the highly flammable acid? H2So4 HCN HCl HNo3 Reveal answer Fill a bubble to check yourself B Correct answer Explanation Hydrocyanic acid (HCN) is highly flammable and volatile, unlike the other common mineral acids listed which are corrosive but not combustible. HCN can form explosive mixtures with air and requires special handling precautions.