Answer:
Percentage abundance of B 10 is = 20 %
Percentage abundance of B 11 is = 80 %
Explanation:
The formula for the calculation of the average atomic mass is:
Given that:
Since the element has only 2 isotopes, so the let the percentage of first be x and the second is 100 -x.
For first isotope, B 10:
% = x %
Mass = 10.0129 u
For second isotope, B 11:
% = 100 - x
Mass = 11.0093 u
Given, Average Mass = 10.81 u
Thus,

Solving for x, we get that:
x = 20 %
Thus percentage abundance of B 10 is = 20 %
Percentage abundance of B 11 is = 100 - 20 % = 80 %
The o-xylene, m-xylene, and p-Xylene are constitutional isomers. The correct option is D.
<h3>What are isomers?</h3>
Isomers are the elements or polyatomic elements that have similar molecular formula.
All options are attached here:
A.optical isomers
B.structural isomers
C.geometric isomers
D.constitutional isomers
Thus, the correct option is D.constitutional isomers.
Learn more about isomers
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6.023 x 10^23 . Common salt . Total of 12.046 x 10^23 atoms