Physics

Problem

A sample of

^{90}

Sr has an activity of

4.0\times10^{7}\,\text{Bq}

at the instant it is taken from a reactor. The half-life of

^{90}

Sr is

28\,\text{y}

. (a) Calculate the decay constant of the isotope. (b) Find the total number of

\beta^{-}

particles that will be emitted by this sample during the first

7.0\,\text{y}

after removal from the reactor.