HELP ASAP!!!! After a radioactive atom decays, it is the same element that it was before with no measurable change in mass. Which kind of decay has occurred, and how do you know?
1)alpha decay because alpha particles have no mass
2)beta decay because this kind of decay cannot change one element into another 3)alpha decay because it creates a new isotope of the same element
4)gamma decay because photons have no mass