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.
[tex]_A^Z\textrm{X}\rightarrow _{A-2}^{Z-4}+_2^4\alpha[/tex]
Half life is the time taken by an element to decay to half of its initial value.