4个数字复式二中二有几组

简介：Black gunpowder is one of the four great inventions of ancient China. Its main chemical components are potassium nitrate, sulfur and carbon. When encountering an open flame, potassium nitrate decomposes and releases oxygen, causing charcoal and sulfur to burn violently, instantly producing a large amount of nitrogen, carbon dioxide and other gases, and releasing a large amount of heat energy, thus forming an explosion.