Answer:
38400 atoms
Explanation:
The half - life is the time taken for a radioactive material to decay by half. When the half-life time elapses, a material becomes halved.
Since the half-life is 12yrs;
number of atoms now = 2400atoms
Unknown:
Number of atoms in the sample 48yrs ago;
Solution:
In 48yrs, we have 4 half-life counts:
Last 12yrs;
2(2400) = 4800atoms
Last 24yrs
2(4800) = 9600 atoms
Last 36yrs
2(9600) = 19200 atoms
Last 48yrs
2(19200) = 38400 atoms
