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