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%
Potential energy is an object’s stored energy when it is not moving. Kinetic energy is an object’s energy in motion. You can’t be both moving and not moving at the same time, so PE and KE cannot be equal.
Experimental Evidence.
Scientists conduct experiments or observations to gather evidence that either support or disprove a given hypothesis. Hence, all the scientific explanations are based on this body of observations.
The answer is C. that liquids and gases both take the shape of their container.
Think of it this way, if you take an ice cube and put it in your glass, it will stay in its shape and stay that way until it melts. But if you put liquid or a gas into a glass, it will take the shape of the glass that it is put into.
If Biker 1 has less mass than Biker 2 it the follows that biker 1 has a greater acceleration than Biker 2.
<h3>What is the Newton second law?</h3>
The Newton second law gives the relationship between the force and the acceleration. We know that; acceleration = Force/mass.
Now if Biker 1 has less mass than Biker 2 it the follows that biker 1 has a greater acceleration than Biker 2.
Learn more about Newton's law:brainly.com/question/27573481
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