The decay constant of radio isotope is `lambda`. If `A_(1) and A_(2)` are its activities at times `t_(1) and t_(2)` respectively, the number of nuclei which have decayed during the time `(t_(1)-t_(2))`

Options

A. `A_(1)t_(1)-A_(2)t_(2)`
B. `A_(1)-A_(2)`
C. `(A_(1)-A_(2))//lambda`
D. `lambda(A_(1)-A_(2))`

Answer

C

Explanation

`A_(1) = lambdaN_(1),A_(2) =lambdaN_(2)`
`N_(1)-N_(2) = (A_(1)-A_(2))/(lambda)`