In a sample of radioactive material, what percentage of the initial number of active nuclei will decay during one mean life ?

Options

A. `37%`
B. `50%`
C. `63%`
D. `69.3%`

Answer

C

Explanation

`N' = N_(0) (1-e^(-lambdat))`
`t = bar(T) = (1)/(lambda)`
`(N')/(N_(0)) = 1-e^(-lambda.1//lambda) = 1-(1)/(e) = 1-(1)/(2.71) = (1.71)/(2.71) = 0.63`
i.e. `63%`