When is a train on Earth in motion relative to the sun? A It is relative to the sun only when the train is not moving. B It is never in motion relative to the sun. C It is relative to the sun only when the train is moving. D It is always in motion relative to the sun.

Daughter element the new element produced along with a decay particle in a nuclear transmutation 2. half-life the substance that decays in a nuclear transmutation 3. parent element the change of one chemical element into another by nuclear decay or radioactive bombardment 4. transmutation the time required for the decay of one-half of the atoms in a sample of radioactive material