The average atomic mass of the copper from the two given copper isotopes is 63.55
Explanation:
The average atomic masses of the isotopes of an element is calculated by the addition of the masses of the two isotopes in proportionality to their percentage of natural occurrence.
Cu-63 relative abundance 69.17 Atomic mass 62.93
Cu-65 relative abundance 30.83 Atomic mass 64.94
Average atomic mass= Cu 63 Atomic mass*relative occurrence percentage+ Cu 65 Atomic mass*relative occurrence percentage
62.93*0.692+64.94*0.308
= 63.546 amu is the average atomic mass of copper.
