Final answer:
Uranium-235 is preferred in nuclear reactors due to its stable nature as an isotope and its capability to produce enough neutrons for a chain reaction.
Step-by-step explanation:
Uranium-235 is considered ideal for nuclear reactors because of its stable nature as an isotope and its ability to produce enough neutrons to maintain a chain reaction.
Unlike Uranium-238, which is more abundant, Uranium-235 is fissionable, meaning it can split into two smaller atoms and release energy.
This characteristic allows U-235 to sustain the nuclear fission process and produce a significant amount of heat and high-energy radiation, which can be harnessed to generate electricity in nuclear power plants.