Question

PLEASE HELP ME WITH THIS ONE QUESTION

The half-life of Barium-139 is 4.96 x 10^3 seconds. A sample contains 3.21 x 10^17 nuclei. How much of the sample is left after 1.98 x 10^4 seconds?

Answer 1

`A=2.01×10^(16)\:\text{nuclei}`

Step-by-step explanation:

Given:

`\lambda = 4.96×10^3 s`

`A_0 = 3.21x10^(17)` nuclei

t = 1.98×10^4 s

`A=A_02^{-(t)/(\lambda)}`

`A=(3.21×10^(17)\:\text{nuclei}) \left(2^{-(1.98×10^4)/(4.96×10^3)} \right)`

`\:\:\:\:\:\:\:=2.01×10^(16)\:\text{nuclei}`