A sample contains `10^(-2)` kg of two substances A and B with half lives of 4 and 8 sec repsectively (Given that atomic mass of B is twice of A ).
The ratio of average life of A and B is :

Options

A. `3 : 2`
B. `2 : 1`
C. ` 4 : 1`
D. `3 : 4`

Answer

C

Explanation

`r_(A) = (0.693)/(4) xx (10)/(a) xx N_(A)` (Let a is atomic mass of A, then )
`r_(B) = (0.693)/(8) xx (10)/(2a) xx N_(A) " "therefore (r_(A))/(r_(B)) = 4`