A sample of a radioactive element has a mass of `10 g` at an instant `t=0`. The approxiamte mass of this element in the sample after two mean lives is .

Options

A. `2.50 gm`
B. `3.70 gm`
C. `6.30 gm`
D. `1.35 gm`

Answer

D

Explanation

(d) `M = M_0 e^(- lamda t)`, given `t = 2((1)/(lamda))`
`rArr M = 10 e^(- lamda((2)/(lamda))) = 10 ((1)/(e))^2 rArr M = 1.35 gm`.