Answer:

Explanation:
Position vector of the point of application of point of application of force is given as

now we have have force

now the moment of force is given as




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>During 1970s, same observations were seen as what we have observed today pertaining to our climate. Journals were discussing that there would be warming because of greenhouse gases emissions. Also, it was observed between the years 1970 to 1990 that there was a steady surface temperature increase. Due to this, people are now fixated with global warming rather than on global cooling.</span>