Rubidium has two naturally occurring isotopes, rubidium - 85 (atomic mass = 84.9118 amu; abundance = 72.15%) and rubidium - 87 (atomic mass = 86.9092; abundance = 27.85%). Calculate the atomic weight of rubidium

The answer to your question is: 85.458 amu

Explanation:

data

Rubidium-85 A = 84.9118 amu abundance = 72.15%

Rubidium - 87 A = 86.9092 amu abundance = 27.85%

Atomic weight = ?

Atomic weight = 84.9118 (0.7215) + 86.9092 (0.2785)

Atomic weight = 61.2538 + 24.2042

Atomic weight = 85.458 amu