If `N_(0)` is the original mass of the substance of half - life period `t_(1//2) = 5 year` then the amount of substance left after `15` year is

Options

A. `N_0 //16`
B. `N_0//4`
C. `N_0//8`
D. `N_0//2`

Answer

B

Explanation

`N/N_0 = (1/2)^(t//t) = (1/2)^(15//5) = (1/2)^3 = 1/8`
`therefore N= (N_0)/(8)`