The two different isotopes have weights :
w1 = 78.918 amu
w2 = 80.916 amu
average weight w3 = 79.903 amu
The mixing of two components can be modeled as
let the fraction of w1 be 'x'
hence 
now this is a linear equation in 'x'. Substituting the values we get
x = 0.507
hence the percentage of Br79 = 50.7% and the percentage of BR81 = 49.3%
<span>Fossils provide solid evidence that organisms from the past are not the same as those found today; they show a progression of evolution. Scientists calculate the age of fossils and categorize them to determine when the organisms lived relative to each other. Hope this helps</span>
Answer:
small marble
Explanation:
A nonpareil are confectionery tiny ball items that are made up of starch and sugar. It is very small of the size of sugar crystal or sand grains. They were the miniature version of the comfits. They are generally opaque white but bow available in all colors.
In the context, if the nucleus is compared to the size of a nonpareil then its atom would be of the size of small size marble. An atom is bigger in size than that of nucleus as the nucleus is located inside the atoms.
After the great 1906 San Francisco earthquake, geolophysicistHarry Fielding Reid examined the displacement of the ground surface along the San Andreas Fault. He concluded that the quake must have been the result of the elastic reboundof the strain energy in the rocks on either side of the fault.
strain energy is 0. 5x force x (compression) X (compression)
There is a lot of force and a bit of compression when rocks squash up against other rocks causing earthquakes
Frequency:
Frequency is defined as number of events occurring per second.
- Mathematically written as

- The dimensions
are
![[f]=\frac{1}{[T]}](https://tex.z-dn.net/?f=%5Bf%5D%3D%5Cfrac%7B1%7D%7B%5BT%5D%7D)
as
![[T]=[S]](https://tex.z-dn.net/?f=%5BT%5D%3D%5BS%5D)
so,
![[f]=[S^{-1}]](https://tex.z-dn.net/?f=%5Bf%5D%3D%5BS%5E%7B-1%7D%5D)