The activity of a radioactive sample is measured as `9750` counts per minute at `t = 0` and as `975` counts per minute at `t = 5` minutes. The decay constant is approximately

Options

A. `0.230` per minute
B. `0.461` per minute
C. `0.691` per minute
D. `0.922` per minute

Answer

B

Explanation

(b) `A = A_0 e^(-lamda t) rArr 9750 e^(-lamda xx 5) rArr e^(5 lamda) = 10`
`rArr 5lamda = log_e 10 = 2.3026 log_10 10 = 2.3026`
`lamda = 0.461`.