Strontium consists of four isotopes with masses and their percent abundance of 84. amu (0.5%), 86 amu (9.9%), 87amu (7.0 %), and 88. amu (82.6 %). Calculate the relative average atomic mass of Sr?

The answer to your question is: 87.712 amu

Explanation:

Strontium isotopes 1 mass 84 amu abundance 0.5%

2 mass 86 amu abundance 9.9 %

3 mass 87 amu abundance 7%

4 mass 88 amu abundance 82.6%

average atomic mass = (84 x 0.005) + (86 x 0.099) + (87 x 0.07) + (88x0.826)

average atomic mass = 0.42 + 8.514 + 6.09 + 72.688

average atomic mass = 87.712 amu