Final answer:
The physical half-life of 133Xe is the decay time for half the radioactive material, while its biological half-life is the time for half the material to be eliminated by the body.
Step-by-step explanation:
The physical half-life of 133Xe is the time it takes for half of the radioactive material to decay. The biological half-life refers to how long it takes for half of the substance to be removed from a biological system, such as the human body, through metabolic processes.
The actual values for the physical and biological half-lives of 133Xe vary and are specific to the isotope. For example, the physical half-life of Iodine-131 is 8.1 days and the biological half-life is influenced by the body's metabolism of iodine.