Plutonium-239 is one of the isotopes used for fuel in nuclear power plants. It has a half life of 24,000 years. If 100 grams of it were left in a hole, how long until there is only 12.5 grams remaining?

Which statement is true according to the kinetic theory? a. molecules of different gases with the same mass and temperature always have the same average density. b. molecules of different gases with the same mass and temperature always have the same average volume. c. molecules of different gases with the same mass and temperature always have the same pressure. d. molecules of different gases with the same mass and temperature always have the same molecular mass. e. molecules of different gases with the same mass and temperature always have the same average kinetic energy.