Out of the following, which one is least commonly emitted by radioactive substances?
Elements with a high atomic number have the property of spontaneously emitting invisible, highly penetrating, and high-energy radiation which is known as radioactivity.
In natural radioactive decay, three common emissions occur.
alpha particles ( α )
beta particles, (β)
gamma rays (γ)
Hence Neutrons are least commonly emitted by radioactive substances.
Alpha particles were identified as helium-4 nuclei, beta particles were identified as electrons, and gamma rays as a form of electromagnetic radiation like x-rays except much higher in energy and even more dangerous to living systems.