which feature of nuclear fission reactions allows these reactions to take place in a chain reaction?\no…

which feature of nuclear fission reactions allows these reactions to take place in a chain reaction?\no thermal energy is released and heats up the reactants.\no more smaller atoms form that can undergo fission.\no a larger atom is formed, which can then be split.\no neutrons start the reaction and are released during it.
Answer
Brief Explanations:
In a nuclear fission chain - reaction, a neutron initiates the fission of a heavy - nucleus. During the fission process, more neutrons are released which can go on to cause fission in other nuclei, continuing the chain. Thermal energy release doesn't directly cause the chain - reaction mechanism. Smaller atoms formed are typically stable and don't undergo further fission in the context of the chain - reaction initiation. Fission is about splitting a large atom, not forming a larger one for the chain - reaction to occur.
Answer:
D. Neutrons start the reaction and are released during it.