One isotope of bromine has an atomic mass of 78.92amu and a relative abundance of 50.69%. The other major isotope of bromine has an atomic mass of 80.92amu and a relative abundance of 49.31%. Calculate the average atomic mass.

The average atomic mass is 79.91 amu.

Explanation:

Since  

Atomic mass can be find by Multiplying the relative abundance of each isotope by its atomic mass, then add them together to get the atomic mass of the element.

so

Atomic  mass = (0.5069)(78.92 amu) + (0.4931)(80.92 amu)

                       =79.91 amu

So the Atomic mass of the  bromine is 79.91amu.

increases it