Two protons and two neutrons are released as a result of this reaction. 222/86 Rn-> 218/84 Po

One alpha particle is released (A)

Explanation:

We know that it is one alpha particle because alpha particles release two protons and two neutrons.

Alpha particle is nucleus of a helium-4 atom, which is made of two protons and two neutrons.

Nuclear reaction: ²²²Rn → ²¹⁸Po + α (alpha particle).

Alpha decay is radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and transforms into an atom with an atomic number that is reduced by two and mass number that is reduced by four.