Question

Use Table 1 below to answer the following question: Scientists find a piece of wood that is thought to be from an ancient fire circle. They find that the wood contains an amount of carbon-14 (14C) that is approximately 1/16 of the current atmospheric C14 levels.

If you started with 1 million carbon-14 atoms, how many atoms would remain in the wood? C14 has a t1/2 of 5,750 years. (Only use numbers in your answer)

Answer 1

Time passed Time passed 14C initially present 14C at end of half-life
(half life) (Years)
........................................................................................................................
0 0 1,000,000 1,000,000

1 5750 ..... 5,00,000

2 11500 ..... 2,50,000

3 17250 ..... 1,25,000

4 23000 ..... 62,500

Since, wood sample contained 1/16 of current atmospheric concentration of 14C. It means that sample has crossed 4 half-life. Number atoms left are 4 half life = 62,500