Answer:
C.
Explanation:
Exothermic means the energy of products is lower than energy of reactants. Transition state will always be the highest energy among the two.
People’s ethics and morals can effect what they do with the information they receive from science.
The particles are moving fastest in Region D) 5.
As temperature increases, so does the average kinetic energy (speed) of the molecules.
This is false. The law of constant mass states that no matter WHAT the mass will always still be there, whether it converts to gas etc.
Answer:
Explanation:
The<em> half-life </em>time of a radiactive isotope (radioisotope) is a constant value, meaning that the amount of the radioisotope that decays will be (1/2) raised to the number of half-lives passed.
Naming A₀ the initial amount to the radioisotope, you can build this table to find the amount left.
Number of half-lives amount of radiosotope left
0 A₀
1 (1/2) × A₀
2 (1/2)×(1/2)×A₀ = (1/2)² × A₀
3 (1/2)³ ×A ₀
4 (1/2)⁴ × A₀
n (1/2)ⁿ × A₀
Now calculate the number of half-lives the strontium-90 sample has passed after 100 years:
- n = 100 years / 28.1 years ≈ 3.5587
Hence, the amount of strontium-90 is:
![(\frac{1}{2})^{3.5587}A_0=0.08486A_0](https://tex.z-dn.net/?f=%28%5Cfrac%7B1%7D%7B2%7D%29%5E%7B3.5587%7DA_0%3D0.08486A_0)
In percent, that is:
![(0.08486A_0/A_0).100=8.486%](https://tex.z-dn.net/?f=%280.08486A_0%2FA_0%29.100%3D8.486%25)
Rounding to two significant figures, that is 8.5%.
<u>Conclusion</u>: <em>The percent of strontium-90 left after 100 yeaers is 8.5% </em>(choice number 4).