During holidays, there are many beautiful fireworks, and each of us can become pyrotechnic. We must remember that careless handling fireworks can pose a threat to life and can lead to accidents.
September 17 Ukraine celebrates the Day of rescuer - a professional holiday of civil defense (Civil Protection) population - emergency services, fire protection and other special groups that are directly involved in the emergency response of technogenic and natural disasters.
Up to the XIII century, people knew only nine chemical elements: seven metals - gold, silver, copper, tin, iron, lead and mercury, as well as two non-metals - sulfur and carbon.