Boron Occurs Naturally in Two Isotopes ¹⁰B and ¹¹B

Multiple Choice

Boron occurs naturally in two isotopes ¹⁰B and ¹¹B. The standard atomic mass of Boron is 10.811. What are the percentage abundances of ¹⁰B and ¹¹B? (Given: exact mass of ¹⁰B = 10.01294 amu and ¹¹B = 11.00931 amu)

A) 50% and 50%
B) 60% and 40%
C) 70% and 30%
D) 90% and 10%
E) 20% and 80%