Chapter 20.4, Problem 20.9E

Interpretation Introduction

Interpretation:

• The decay constant (inunit of /s) of Strontium-90 has to be determined.
• Activity of a sample having $\text{5}{\text{.2×10}}^{\text{-9}}\text{g}$ of Strontium-90 has to be determined.

Concept introduction:

• Half-life: The time taken for one-half of the nuclei in the sample to decay.  The half-life of the sample is independent of the quantity of radioactive material and depends on the decay constant of the nuclide in the sample.
• The decay constant (k) is independent of the quantity of radioactive material however depends only on the character of the nuclide. Various nuclides have various decay constants. The degree of radioactive decay depends on the decay constant and number of radioactive nuclei at specific time ( ${\text{N}}_{\text{t}}$). The rate of decay is directly proportional to the number of radioactive nuclei in a given sample; it is expressed mathematically as,

${\text{Rate = kN}}_{\text{t}}$