A radioactive sample contains 2.2 mg pure \(_{ 6 }^{ 11 }{ C }\) which has half-life period of 1224 second Calculate.
(i) the number of atoms present initially.
(ii) the activity when 5 μg of the sample will be left.

A nucleus of UX₁ has a half-life of 24.1 days. How long a sample of UX₁ will take to change 90% of it to UX₂?

A certain radioactive element disintegrates for an interval of time equal to mean life. What fraction of element disappears? What fraction of element is left?

A radioactive isotope has a half-life of T years. How long will it take the activity to reduce to 3.125% of its original value?

Determine the distance of closest approach when an alpha particle of kinetic energy 4.5 MeV strikes a nucleus of Z = 80, stops and reverses its direction.