Chemistry

Problem

Magnesium has two principal isotopes with masses

24.00\,\text{amu}

and

25.00\,\text{amu}

. If the average atomic mass of magnesium is

24.31\,\text{amu}

, what is the percent abundance of the heavier isotope,

^{25}

Mg? a) 69 % b) 45 % c) 31 % d) 16 %