The half-life period of a redioactive element is 20 days. What will be the remaining mass of 100 g of it after 60 days ?

Options

A. 25 g
B. 50 g
C. 12.5 g
D. 20 g

Answer

C

Explanation

( c ) : 60 days = 3 half-lives, i.e., n = 3 , `[A]=([A]_(0))/(2^(n))=(100)/(2^(3))=(100)/(8)=12.5g`