A 256-gallon barrel of radioactive Urikium is spilled at a factory. The entire area is evacuated! Experts say that the area can be deemed safe after only 2 gallons remain. Unfortunately, it is too toxic for any clean-up efforts, so residents will just have to wait for the Urikium to evaporate, Fortunately, Urikium has a half-life of only three hours. That means that half of the Urikium will evaporate every three hours HELP