Iodine is 80% 127I, 17% 126I, and 3% 128I. Calculate the average atomic mass of Iodine.

Given

80% 127I, 17% 126I, and 3% 128I.

Required

The average atomic mass

Solution

The elements in nature have several types of isotopes

Atomic mass is the average atomic mass of all its isotopes

Mass atom X = mass isotope 1 . % + mass isotope 2.% + ... mass isotope n.%

Atomic mass of Iodine = 0.8 x 127 + 0.17 x 126 + 0.03 x 128

Atomic mass of Iodine = 101.6 + 21.42 + 3.84

Atomic mass of Iodine = 126.86 amu

the answer is c i believe

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