Multiple choice general knowledge science & technology Potassium nitrate Soap Saltpeter Epsomasalt Aspirin Reveal answer Fill a bubble to check yourself B Correct answer Explanation Potassium nitrate (KNO3) is commonly known as saltpeter (or saltpetre). It has been historically important as a component of gunpowder, food preservative, and fertilizer. The chemical formula KNO3 consists of potassium, nitrogen, and oxygen.