Thorium-232 is known to undergo a progressive decay series until it reaches stability at lead-208. For each step of the series indicated in the table below, indicate which nuclear particle(s) is/are emitted. Parent Nuclide Particle Emitted Th-232 Ra-228 Ac-228 Th-228 Ra-224 Rn-220 Po-216 Pb-212 Bi-212 Po-212 Pb-208