Sorry i cant even read that
Answer:
transfer pipet that had markings every 0.1 mL.
Explanation:
<u>Answer: </u>
A sample initially contained 150 mg of radon-222. After 11.4 days only 18.75mg of the radon-222 in the sample remained where 3 half-lives have passed
<u>Explanation:</u>
Given, the initial value of the sample,
= 150mg
Final value of the sample or the quantity left, A = 18.75mg
Time = 11.4 days
The amount left after first half life will be ½.
The number of half-life is calculated by the formula
![\frac{A}{A_{0}}=\left(\frac{1}{2}\right)^{N}](https://tex.z-dn.net/?f=%5Cfrac%7BA%7D%7BA_%7B0%7D%7D%3D%5Cleft%28%5Cfrac%7B1%7D%7B2%7D%5Cright%29%5E%7BN%7D)
where N is the no. of half life
Substituting the values,
![\frac{18.75}{150}=\left(\frac{1}{2}\right)^{N}](https://tex.z-dn.net/?f=%5Cfrac%7B18.75%7D%7B150%7D%3D%5Cleft%28%5Cfrac%7B1%7D%7B2%7D%5Cright%29%5E%7BN%7D)
![\left(\frac{1}{2}\right)^{3}=\left(\frac{1}{2}\right)^{N}](https://tex.z-dn.net/?f=%5Cleft%28%5Cfrac%7B1%7D%7B2%7D%5Cright%29%5E%7B3%7D%3D%5Cleft%28%5Cfrac%7B1%7D%7B2%7D%5Cright%29%5E%7BN%7D)
On equating, we get, N = 3
Therefore, 3 half-lives have passed.