The decay constant for the radioactive nuclide `64Cu` is `1.516 xx 10^(-5) s^(-1)` . Find the activity of a sample containing `1mug` of `64Cu`. Atomic weight of copper = 63.5 g mole^ (-1). Neglect the mass difference between the given radioisotope and normal copper.

Explanation

`63.5 g` of copper has `6 xx 10^23` atoms. Thus, the number of atoms in `1 mug` of `Cu` is
`N = ((6 xx 10^23) xx 1 mug))/(63.5 g) = 9.45 xx 10^15`.
The activity `= lambdaN`
`=(1.516 xx 10^(-5) s^(-1) xx (9.45 xx 10^15)`
= 1.43 xx 10^11 disintegrations s^(-1)`
`= (1.43 xx 10^11)/(3.7 xx 10^10` Ci = 3.86 Ci`.