An element is a mixture of two isotopes. one isotope has an atomic mass of 34.96885 amu and has an abundance of 75.53%. the other isotope has an atomic mass of 36.96590 amu. calculate the average atomic mass and identify the element?

35.4575 amu

Explanation:

We use the relative abundance of each of the isotopes.

Let the isotopes be A and B.

Since A is having an abundance of 75.53, the abundance of B would be 100 - 75.53 = 24.47%

The average atomic mass is calculated as follows;

(75.53/100 * 34.96885)  + (24.47/100 * 36.96590) = 26.4119 + 9.0456 = 35.4575 amu

i'm assuming that it's c.) red bank..