### Theory:

Alpha decay:
Alpha decay is a nuclear reaction in which an unstable parent nucleus emits an alpha particle and forms a stable daughter nucleus.
The decay of Uranium ($$U^{238}$$) to Thorium ($$Th^{234}$$) with the emission of an alpha particle.

As the parent nucleus emits an $$α -\ particle$$ during the decay, it is evident that the mass number of the daughter nucleus reduces by four and the atomic number decreases by two.

Alpha decay process
Beta decay:
Beta decay is a nuclear reaction in which an unstable parent nucleus emits a beta particle and forms a stable daughter nucleus.
Beta decay of phosphorous is a good example.


In $$β-\ decay$$, the atomic number increases by one, but there is no change in the mass number of the daughter nucleus.
Beta decay process

Important!
NOTE: The atomic number of the resulting nucleus identifies the product nucleus in a nuclear reaction.
Gamma decay:
In gamma decay, only the energy level of the radioactive nucleus changes, but the atomic number and mass number remains the same.

Gamma decay process

In radioactive decay, both $$α$$-decay and $$β$$-decay never take place together in a single process. Either $$α$$-decay or $$β$$-decay occurs along with the emission of $$γ$$ particles.
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