A certain nuclide has a half-life period of 30 minutes. If a sample containing 600 atoms is allowed to decay for 90 minutes, how many atoms will remain.

Options

A. 200 atoms
B. 450 atoms
C. 75 atoms
D. 150 atoms

Answer

C

Explanation

`t_(1//2) = 30, T = 90 :.n = (T)/(t_(1//2)) = (90)/(30) = 3`
`:.` Number of half lives = 3
We know that `N = ((1)/(2))^(n) N_(0)`
`:. N` (Number of atom left after) ` = ((1)/(2))^(3) xx 600` disintegration)
`:. N = (1)/(8) xx 600 - 75` atoms