Answer:
78.85
Explanation:
To calculate the average atomic mass of the isotopes we use the given masses and abundances, as follows:
- Mass of Isotope 1 * Abundance of Isotope 1 + Mass of Isotope 2 * Abundance of Isotope 2 + ....
In other words:
- 78 amu * 75/100 + 81 amu * 15/100 + 82 amu * 10/100 = 78.85
So the answer is 78.85.
