A student is investigating the radioactive decay of a short-lived isotope using a Geiger-Müller (GM) tube and a counter.
State one natural source of background radiation.
Describe the method the student should use to measure and correct their experimental results for background radiation.
Before starting the experiment, the student measures the background radiation inside the lab. They record a total of 150 counts over a period of 5 minutes. Calculate the average background count rate in counts per minute (cpm).
The student then places the radioactive sample near the GM tube and records the total count rate (including background). At t=0 minutest = 0\text{ minutes}t=0 minutes, the total count rate is 270 cpm270\text{ cpm}270 cpm. At t=10 minutest = 10\text{ minutes}t=10 minutes, the total count rate is 90 cpm90\text{ cpm}90 cpm. Calculate the corrected count rate of the sample at both t=0 minutest = 0\text{ minutes}t=0 minutes and t=10 minutest = 10\text{ minutes}t=10 minutes.
Use your answers to part (ii) to calculate the half-life of this isotope. Show your working.
Technetium-99m is a gamma emitter with a half-life of 6 hours6\text{ hours}6 hours and is commonly used as a radioactive medical tracer to diagnose conditions inside the human body. Explain why Technetium-99m is highly suitable for this role. Refer to both its emission type and its half-life in your answer.
