Question

Calculate the number of neutrons produced along with $_{ 54 }^{ 139 }{ Xe }$ and $_{ 38 }^{ 94 }{ Sr }$ from the absorption of a slow neutron by $_{ 92 }^{ 235 }{ U }$.

Answer 1

Nuclear reaction: It is defined as a process, such as fission, fusion, or radioactive decay, in which the structure of an atomic nucleus is altered through the release of energy or mass or by being broken apart.

Complete answer:
The neutron is the particle present in the atomic nucleus along with a proton with a mass = ${ 1 }$ and charge = ${ 0 }$.
The balanced nuclear reaction will be as follows:
$_{ 92 }^{ 235 }{ U+2_{ 0 }^{ 1 }{ n\rightarrow _{ 38 }^{ 94 }{ Sr+_{ 54 }^{ 139 }{ Xe } } } }$
Total mass conserved = ${ 2(1) + 235 = 139 + 94 }$
Hence, the number of neutrons produced are ${ 2 }$.

Additional Information:
In the case of nuclear reactions, the law of conservation of mass is replaced by the law of conservation of mass and energy. During a nuclear reaction, the mass of reactants may be more than the products. The lost mass is changed over an enormous measure of energy.
According to this law, ‘the total amount of matter and energy stays constant in an isolated system’.
Nuclear Fusion reactions: These are those reactions wherein two small nuclei fuse together to form a greater nucleus, with the development of a large amount of energy (almost three to multiple times greater than nuclear fission reaction).
Nuclear fission reactions: These are those reactions in which a greater nucleus breaks into two or smaller nuclei upon bombardment with high-speed particles like a neutron, with the emission of alpha particles/beta particles/ gamma rays.

Note: The possibility to make a mistake is that don’t confuse between gamma rays and neutrons, gamma rays are neutral species while neutrons have zero atomic number and ${ 1 }$ atomic mass.