Magnesium has two principal isotopes with masses and

CHEMISTRY · Single correct · A Level · Chemistry · Atomic structure · Atomic structure

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 %