State the definition of half-life.
The half‐life of Cobalt‐60 is 5 years.
The count‐rate of a sample of Cobalt‐60 is 100 counts per minute.
Higher Only
Calculate the count‐rate of the Cobalt‐60 after 10 years.
A radioactive isotope can be used as a tracer in a patient’s body. It is monitored by a radiation detector outside the body.
Four possible radioactive isotopes are shown in Table 1
Table 1
Radioactive isotope | Type of radiation emitted | Half-life |
Radon‐222 | Alpha | 3.8 days |
Iodine‐131 | Gamma | 8 days |
Cobalt‐60 | Gamma | 5 years |
Americium-241 | Alpha | 470 years |
Which radioactive isotope from the table is best to use as a medical tracer?
Explain your answer.
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