Final answer:
To find the relative abundance of B-10 and B-11, you need to set up and solve an equation using their individual masses and the given average atomic mass of boron. Solving gives the percentage of B-10, and subtracting that from 100 provides the percentage of B-11.
Step-by-step explanation:
To calculate the percentage relative abundance of B-10 and B-11, we use the given average atomic mass of boron (10.804 amu) and the precise masses of its isotopes. The isotope B-10 has a mass of 10.0129 amu and isotope B-11 has a mass of 11.00931 amu. The formula to calculate the average atomic mass is:
Average atomic mass = (% abundance of B-10 × mass of B-10) + (% abundance of B-11 × mass of B-11)
Let the % abundance of B-10 be x, and thus % abundance of B-11 will be 100 - x. We can write the equation as:
10.804 = (x × 10.0129) + ((100 - x) × 11.00931)
You solve for x to get the percentage of B-10 and subtract x from 100 to get the percentage of B-11.