What happens to a radioactive isotope as it decays? does the radioactive material disappear? explain

I think you are asking, what about the rest of the mass? The radioactive isotope decays into another element (such as Uranium decaying to Thorium or something similar) and a particle like alpha particle, beta particle, gamma ray, etc depending on the type of decay it is undergoing.

I’m pretty sure it’s false i’m not sure

Particle exchange energy though elastic collision , hope this .