A 1.00 mg sample of a radioactive isotope Z has a half-life of 2.0 d
CHEMISTRY · Subjective · US High School · Chemistry · Atomic Structure & Nuclear · Atomic Structure & Nuclear
Problem
A 1.00 mg sample of a radioactive isotope Z has a half-life of 2.0 d. The sample is allowed to decay for 3.0 d and is then split equally into two portions A and B. Portion A is sealed so that no further decay occurs, while portion B is left to decay for another 5.0 d.
(i) Calculate the mass of undecayed isotope present in portion A at the moment it is sealed.
(ii) Determine the mass of undecayed isotope present in portion B at the end of the additional 5.0 d.
(iii) The two portions are now recombined. Find the total mass of undecayed isotope at this instant and express it as a percentage of the original 1.00 mg.