Radioactivity

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 5500 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 16500 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 1/32^nd 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.  

a)       choose the best tracer for each of the following tasks (choose the letter A, B, C or D)

i)  dating an Egyptian mummy  choose a letter A B C D                                             

ii)  searching for a leak in a pipeline    choose a letter A B C D                 

iii)  use in a smoke alarm      choose a letter A B C D                                       

iv) checking the thickness of paper in a paper factory     choose a letter A B C D    

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