1. Radio-carbon dating is used to estimate the age of objects that were once living as all living things contain a small amount of Carbon-14, which has a half-life of 5700 yrs. By measuring the activity (counts min-1) of the dead tissue its approximate age can be determined. Show all the steps in your working out.

a. A sample of living wood has an activity of 16 counts min-1 per gram. Calculate the activity of a 20g sample of living wood.

b. Calculate the activity of 20g sample of wood from a tree that died 17100 years ago. State the correct units in your answer

c. A 5g of old wood from an archaeological site has an activity of 20 counts min-1, what was the activity of the wood when it was living? How long ago did the tree died?

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