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)//2`
B. `N_(0)//3`
C. `N_(0)//4`
D. `N_(0)//8`

Answer

D

Explanation

Number of half lives `=(15)/(5)=3`
`therefore" "(N)/(N_(0))=((1)/(2))^(n)=((1)/(2))^(3)=((1)/(8)) therefore N=(N_(0))/(8)`