Question

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Full explanation required!!

Answer 1

Let abundance of B-10 be x
Then abundance of B-11 will be 100-x
Formula of average atomic mass is
$\frac{m1 \times n1 + m2 \times n2...}{n1 + n2...}$
Where m is the atomic mass and n is the percentage
Substituting the above values,
$10.8 = \frac{10x + 11(100 - x)}{100} \\ 1080 = 10x + 1100 - 11x \\ - x = - 20 \\ x = 20\%$
So, abundance of B-10 is 20% and abundance of B-11 is 80%