Answer;
-Helium atom
Explanation;
-An alpha particle is identical to the nucleus of a helium atom.
-Alpha particle is one type of particles emitted during a radioactive decay, others being gamma and beta particles. Alpha particles are produced during the process of alpha decay.
-When an alpha particle is generated during a radioactive decay, the mass number of the radioactive particle increases by 2 while the atomic number increases by 4.