What would happen if the earth`s core was made of radio-active elements? No website is giving the answer
Radioactive decay is the reason why some planet core is still molten. This is also the case for Earth.
Radioactive elements decay, emitted radiation (be it gamma, beta or alpha) is absorbed by the atoms in the core and converted to heat.
Mars is believed to have lost this heat source some time ago, undergoing shrinkage (which is supposed to be the trigger for the creation of Valles Marineris) and losing the dynamo generating the magnetic field.