Chapter 19, Problem 23A

Interpretation Introduction

Interpretation: The given isotopes are to be arranged in order of their relative decay activities.

Concept introduction: The rate at which an isotope decays is called its activity and half-life of a radioactive sample is the time taken by it to reduce its concentration to half. If an isotope has shorter half-life, it has more activity and when an isotope has longer half-life, it has less activity.

Answer to Problem 23A

Increasing order of isotope’s decay activities is as follows:

  ${}^{14}C{<}^{3}H{<}^{60}Co{<}^{131}I{<}^{24}Na$

Explanation of Solution

  ${}^{24}Na$ has the shortest half-life followed by, ${}^{131}I$ , ${}^{60}Co$ , ${}^{3}H$ and ${}^{14}C$ . The isotope with shortest half-life will show maximum activity as it takes minimum time to decay to half its concentration.

Conclusion

Thus, the increasing order of isotope’s decay activities is:

  ${}^{14}C{<}^{3}H{<}^{60}Co{<}^{131}I{<}^{24}Na$