1. Radon is a naturally occurring radioactive gas. It comes from uranium in rocks and soils.
a) Explain what the word radioactive means
b) Explain the danger of breathing radon gas into the lungs
2. Carbon 14 is a radioactive element with a half life of 5570 years. It is used for dating ancient bones. A sample of living bone contains 80 units of Carbon 14.
a) An ancient bone contains 5 units of carbon 14. How old is the bone ?
b) How many units of carbon 14 would be found in a bone that was 16710 years old ?
3. Horsforth School has a Cobalt 60 radioactive source which is 20 years old. It emits beta particles and has a half life of 5 years.
a) Why must the source be handled with tweezers and held away from the body ?
b) The source is no longer any use when its radioactivity has decayed to 1/32nd of its original value. In how many years does it need replacing ?
4. Look at the list of four radioactive tracers in the table below.
|
Element |
Radiation emitted |
Half life |
|
Cobalt 60 |
beta |
5 years |
|
Americium 241 |
alpha |
460 years |
|
Carbon 14 |
beta |
5570 years |
|
Technetium 99 |
gamma |
6 hours |
a) choose the best tracer for each of the following tasks (write the name of the element)
i) dating an Egyptian mummy
ii) searching for a leak in a pipeline
iii) use in a smoke alarm
iv) checking the thickness of paper in a paper factory
v) checking a weld in metal pipes
vi) a medical investigation of a possible kidney infection