The radioactive decay obeys first order kinetics
the rate law expression for radioactive decay is
![ln\frac{[A_{0}]}{[A_{t}]}=kt](https://tex.z-dn.net/?f=ln%5Cfrac%7B%5BA_%7B0%7D%5D%7D%7B%5BA_%7Bt%7D%5D%7D%3Dkt)
Where
A0 = initial concentration
At = concentration after time "t"
t = time
k = rate constant
For first order reaction the relation between rate constant and half life is:
Let us calculate k
k = 0.693 / 72 = 0.009625 years⁻¹
Given
At = 0.25 A0
time = 144 years
So after 144 years the sample contains 25% parent isotope and 75% daughter isotopes**
Simply two half lives
Answer:
Key Points. Ionic bonds are formed through the exchange of valence electrons between atoms, typically a metal and a nonmetal.
Explanation:
Nitrogen molecule is diatomic, whereas other elements form tetraatomic molecules.
Answer:
A
Explanation:
Developing work ethics won't lower your stress although it may make your conscience a little happier. Not B
Not C. Procrastinating just makes things harder. The mountain of things to do is not diminishing at all and your stress knows it.
Not D. Although D is the second best answer, setting goals is not really an action. It is a plan for how to work. But it is not work. Still having a goal is useful.
The answer is A. Just keep hitting what you have to do at a steady pace.
