When radon$-228$ undergoes alpha decay, the radon$-228$ nuclide emits$$a H nucleusan electrona neutrona He nucleusa proton, the mass number$$decreasesincreases$$by four and the number of protons$$increasesdecreases$$by two.

Alpha decay normally occurs in$$heavy nuclei with too large a p$/$n ratioheavy nuclei with too large a n$/$p ratiolight nuclei with too large a p$/$n ratiolight nuclei with too large a n$/$p ratio.

The daughter nuclide formed by the alpha decay of Rn$-228$ is$$Th$-230$Ra$-232$Po$-224$Pb$-226$