Answer:
Amount of chromium-51 remaining after 83.1 days = 0.031 mg
Explanation:
Radioactive disintegration follows the exponential law which can be mathematically expressed as:
[tex]N(t)=N(0)e^{-0.693t/t1/2}------(1)[/tex]
where N(0) = initial amount of the radioactive substance
N(t): radioactive substance left after time t
t1/2 = half life of the radioisotope
In the case of chromium-51:
N(0) = 0.25 mg
t = 83.1 days
t1/2 = 27.7 days
Substituting these values in equation (1) gives:
[tex]N(t)=0.25e^{-0.693*83.1/27.7} = 0.031 mg[/tex]
