ii) The half-life of a radioactive element is 20 days. Calculate the time taken forthe number of nuclei to decrease to 40% their initial value.iii) Determine the percentage of unstable nuclei remaining after a time / = 3T1/2has elapsed given that 100% of the nuclei are unstable at time = 0. Hence draw afully labelled diagram to show how the activity of a radioactive sample varies withtime.iv) A radioactive source has an activity of 4.2x107 Bq due to the decay of aradioisotope with a half-life of 7500 years. Calculate the decay constant andthe number of undecayed nuclei in the source.

Given Data : Half life of element, t1/2 = 20 days Number of nuclei left = 40% of initial value…

Answered: ii) The half-life of a radioactive…

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ii) The half-life of a radioactive element is 20 days. Calculate the time taken for the number of nuclei to decrease to 40% their initial value.