Answer:
1. Daughter element : the new element produced along with a decay particle in a nuclear transmutation
2. half life: the time required for the decay of one-half of the atoms in a sample of radioactive material
3. parent element : the substance that decays in a nuclear transmutation
4. transmutation : the change of one chemical element into another by nuclear decay or radioactive bombardment
Explanation: Radioactive decay process is a type of process in which a less stable nuclei also called as parent element decomposes to a stable nuclei or a daughter element by releasing some radiations or particles like alpha, beta particles or gamma-radiations and the process by which one element changes to another element is called as transmutation.
Half life is the time taken by an element to decay to half of its initial value.