Chemical change that can be useful and harmful both
Answers
While many chemical reactions are critical to life—the conversion, for instance, of nutrients to water and carbon dioxide, a process that also yields the energy used to fuel cells—still others are quite dangerous. Many toxin-liberating or potentially explosive chemical reactions aren't encountered outside the controlled environment of a laboratory, as the required reagents are rare or controlled, but even household substances, if mixed in the wrong combinations, can liberate poisonous vapors. It's a good idea to be aware of such reactions, and to avoid them at all costs.
Chemical reactions help us to solve crimes and explain mysteries. By analyzing blood and tissue samples, for example, police are able to identify the perpetrators of crimes. Chemical reactions are also the tools we use to date fossils, analyze ancient materials, and better understand how our ancestors lived.
One of the most dangerous chemical reactions is a mixture of cesium with water, because when these two substances come into contact, there is an immediate explosion. This reaction is so dangerous that even if a very little amount of this metal is added to a glass of water, the glass will explode in fragments.