Question

An atom that has 84 protons and 86 neutrons undergoes a reaction. At the end of the reaction, it has 82 protons and 84 neutrons. What happened to the atom?
It accepted radiation in a chemical reaction.
It donated neutrons to another atom in a chemical reaction.
It emitted an alpha particle in a nuclear reaction.
It released a beta particle in a nuclear reaction.

Answer 1

It emitted an alpha particle in a nuclear reaction.

Reason: The atom lost 2 protons and 2 neutrons (mass number decreased by 4 and atomic number by 2), which is exactly an alpha particle (2 p + 2 n).