The half-life of pononium is `140` days. After how many days. `16 gm` polonium will be reduced to `1 gm` (or `15 gm` will decay) ?

Options

A. 700 days
B. 280 days
C. 560 days
D. 420 days

Answer

C

Explanation

( c) `(N)/(N_0) = ((1)/(2))^(t//140) rArr (1)/(16) = ((1)/(2))^(t//140)`
`rArr (t)/(140) = 4 rArr t = 560 days`.