A60.0-g sample of fermium-253 was placed in a sealed vessel 9.0 days ago. only 7.5 g of this isotope is now left. what is the half-life of fermium-253? 3.0 days 4.5 days 17.5 days 20.0 days

Chemical energy is a form of a. kinetic energy only. b. both potential and kinetic energy. c. neither potential nor kinetic energy. d. potential energy only. reset

28. which is not a reason that water is used to store spent fuel rods from nuclear power plants? water increases the speed of the chain reaction in the fuel rods. water protects nuclear power plant workers from the high temperature and radiation of the fuel rods. water acts as a radiation shield to reduce the radiation levels. water cools the spent rods. salts action

What does a numerical subscript following an element in a chemical formula mean?