`99 %` of a radioactive element will decay between

Options

A. `6` and `7` half-lives
B. `7` and `8` half-lives
C. `8` and `9` half-lives
D. `9` half-lives

Answer

A

Explanation

(a) `N = N_0((1)/(2))^n rArr (N)/(N_0) = ((1)/(2))^n rArr (1)/(100) = ((1)/(2))^n `
`rArr 2^n =100`
`n` comes out in between `6` and `7`.