When a free neutron collides with a uranium-235 nucleus and causes that nucleus to fission, the collision fragments contain a total of 2.5 free neutrons, on average, including the original free neutron. The critical mass for uranium-235 is about 50 kilograms. Suppose that another radioactive material, fundamentium-999, undergoes fission when struck by a neutron and the collision fragments contain a total of 0.5 neutrons, on average, including the original free neutron. What would be the critical mass of fundamentium-999?
Infinite. No chain reaction could occur in fundamentium-999.
About 10 kilograms.
About 50 kilograms.
About 250 kilograms.