Question

Broron has two stable isotopes, `._(5)^(10)B` and `._(5)^(11)B`. Their respective masses are 10.01294 u and 11.00931 u, and the atomic mass of boron is 10.811 u. Find the abundances of `._(5)^(10)B` and `._(5)^(11)B`.

Answer 1

Let relative abundance of `._(5)B^(10)` be x %
`therefore` Relative abundance `._(5)B^(11)=(100 - x)%`
Proceeding as above
`10.811 = (10.01294x + 11.00931xx(100-x))/(100)`
`x = 19.9%` and `(100-x)=30.1%`