Question:
The relative atomic mass of boron (which exists
in two isotopic forms 10B and 11B) is 10.81.
What will be the abundance of 10B and 11B,
respectively (consider a sample of 100 atoms)?
The relative atomic mass of boron (which exists
in two isotopic forms 10B and 11B) is 10.81.
What will be the abundance of 10B and 11B,
respectively (consider a sample of 100 atoms)?
Options:
- 19% and 81%
- 81% and 19%
- 38% and 62%
- 62% and 38%
- 19% and 81%
- 81% and 19%
- 38% and 62%
- 62% and 38%
Correct Answer: A) 19% and 81%
Explanation:
Average atomic mass = (abundance_1 * mass_1 + abundance_2 * mass_2) / 100
10.81 = (x*10 + (100-x)*11) / 100 => 1081 = 10x + 1100 – 11x => x = 19% (for B10) and 81% (for B11).
Average atomic mass = (abundance_1 * mass_1 + abundance_2 * mass_2) / 100
10.81 = (x*10 + (100-x)*11) / 100 => 1081 = 10x + 1100 – 11x => x = 19% (for B10) and 81% (for B11).