Question

A radiation counter measures 2.85 x 103 counts s-1 at 9:10 a.m. on Tuesday. In the afternoon, at 13:27, it measures 2.23 x 103 counts s-1. (a). What is the value of the decay constant, in min-1 and in s-1 ? (b). Determine the half life, in minutes. (c). At what day and time will the countrate reach 285 counts s-1 ? (d). Assume that the countrate reported by your instrument is 80.0% of the true decay rate of the sample. At the time you found in (c), how many parent atoms remain?

Answer 1