<u>Answer:</u> The particle released in the given reaction is one alpha particle
<u>Explanation:</u>
In a nuclear reaction, the total mass and total atomic number remains the same.
For the given fission reaction:
Total mass on reactant side = total mass on product side
222 = A + 218
A = 4
Total atomic number on reactant side = total atomic number on product side
86 = Z + 84
Z = 2
The isotopic symbol of unknown element is . Another name of helium atom is alpha particle.
Hence, the particle released in the given reaction is one alpha particle