Which one among the following is used in making gunpowder ?

Gunpowder, historically known as black powder, is a chemical explosive mixture consisting of three primary components: potassium nitrate, charcoal, and sulfur [1]. Potassium nitrate (KNO3), also commonly referred to as saltpeter or niter, serves as the critical oxidizing agent in the mixture [1]. During combustion, it decomposes at high temperatures to release oxygen, which allows the fuel components—charcoal (carbon) and sulfur—to burn rapidly without needing external air. While modern ratios typically settle on 75% potassium nitrate, 15% charcoal, and 10% sulfur, historical variations existed [1]. Other options like magnesium sulphate and calcium sulphate (gypsum) are used in industries such as cement and fertilizers but do not possess the oxidizing properties required for gunpowder [2]. Sodium stearate is a surfactant commonly used in soaps and is unrelated to explosive compositions.

Sources

1. [1] https://www.nps.gov/casa/learn/historyculture/gunpowder.htm
2. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 13: Types of Rocks & Rock Cycle > 13.5. Some Rock-Forming Minerals > p. 175