Answer: Neutrons released act as reactants in next reaction.
Explanation:
Nuclear chain reactions occur in fission reactions only. Nuclear fission reactions are defined as the reactions in which larger nuclide splits into two or more smaller daughter nuclides.
In nuclear chain reaction, the neutrons that are released in the previous fission reaction act as the starting material in the next reaction. Thus, this process continues to many reactions and hence, is known as nuclear chain reaction.
For Example: Uranium-235 on bombardment of 1 neutron undergoes fission reaction producing 3 neutrons and a huge amount of energy. The reaction follows:
[tex]_{92}^{235}\textrm{U}+_0^1n\rightarrow 3_0^1n+_{36}^{92}\textrm{Kr}+_{56}^{141}\textrm{Ba}+\text{energy}[/tex]
Hence, neutrons released act as reactants in next reaction.
