<u>Answer:</u> The average atomic mass of magnesium is 24.307 amu.
<u>Explanation:</u>
Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.
Formula used to calculate average atomic mass follows:
.....(1)
- <u>For isotope:</u>
Mass of isotope = 23.985 amu
Percentage abundance of isotope = 78.994 %
Fractional abundance of isotope = 0.78994
- <u>For isotope:</u>
Mass of isotope = 24.986 amu
Percentage abundance of isotope = 10.001 %
Fractional abundance of isotope = 0.10001
- <u>For isotope:</u>
Mass of isotope = 25.983 amu
Percentage abundance of isotope = 11.013 %
Fractional abundance of isotope = 0.11013
Putting values in equation 1, we get:
Hence, the average atomic mass of magnesium is 24.307 amu.