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

`R= R_(0) e^(-lamda t)`
`rArr 975 = 9750 e^(-lamda xx 5)`
`rArr 5 lamda = ln (10)= 2.303 log_(10) (10)`
`rArr lamda= (2.303)/(5)= 0.461` per minute