Astatine is the rarest naturally occurring element in the Earth's crust. If only about 1.00x1023 atoms of astatine exist at any one time on Earth then what mass in kilograms is that
equivalent to?

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