A physical change does not change the identity of the substance but the chemical change does.
Example
If you tear or shred a piece of paper it is still paper, but if you pour chemicals on it it will probably change to something else.
The number of waves passing in a certain amount of time
Two months later 13.8 milligrams of the barium-131 still be radioactive.
<h3>How is the decay rate of a radioactive substance expressed ? </h3>
It is expressed as:
![A = A_{0} \times (\frac{1}{2})^{t/T}](https://tex.z-dn.net/?f=A%20%3D%20A_%7B0%7D%20%5Ctimes%20%28%5Cfrac%7B1%7D%7B2%7D%29%5E%7Bt%2FT%7D)
where,
A = Amount remaining
A₀ = Initial Amount
t = time
T = Half life
Here
A₀ = 0.50g
t = 2 months = 60 days
T = 11.6 days
Now put the values in above expression we get
![A = A_{0} \times (\frac{1}{2})^{t/T}](https://tex.z-dn.net/?f=A%20%3D%20A_%7B0%7D%20%5Ctimes%20%28%5Cfrac%7B1%7D%7B2%7D%29%5E%7Bt%2FT%7D)
![= 0.50 \times (\frac{1}{2})^{60/11.6}](https://tex.z-dn.net/?f=%3D%200.50%20%5Ctimes%20%28%5Cfrac%7B1%7D%7B2%7D%29%5E%7B60%2F11.6%7D)
![= 0.50 \times (\frac{1}{2})^{5.17}](https://tex.z-dn.net/?f=%3D%200.50%20%5Ctimes%20%28%5Cfrac%7B1%7D%7B2%7D%29%5E%7B5.17%7D)
= 0.50 × 0.0277
= 0.0138 g
= 13.8 mg [1 mg = 1000 g]
Thus from the above conclusion we can say that Two months later 13.8 milligrams of the barium-131 still be radioactive.
Learn more about the Radioactive here: brainly.com/question/2320811
#SPJ1
Disclaimer: The question was given incomplete on the portal. Here is the complete question.
Question: Suppose that 0.50 grams of ban that 0.50 grams of barium-131 are administered orally to a patient. Approximately many milligrams of the barium would still be radioactive two months later? The half-life of barium-131 is 11.6 days.
True! all matter is made out of atoms & molecules