Rubidium Has Two Naturally Occurring Isotopes

question 30

Multiple Choice

Rubidium has two naturally occurring isotopes.The atomic weight of Rb is 85.4678 u.If 72.15% of Rb is found as Rb-85 (84.9117 u) ,what is the mass of the other isotope?

• A) 0.56 u
• B) 85.68 u
• C) 86.68 u
• D) 86.02 u
• E) 83.47 u