Question

gallium is a metal which forms compounds with a wide variety of uses. some of the applications of gallium compounds include computer memory chips, light emitting diodes and lasers. radioactive isotopes of gallium are used to image the human body and locate tumors. naturally occurring gallium consists of two isotopes. one of those isotopes is $^{71}$ga with an isotopic mass of 70.9247050 amu and an abundance of 39.892%. what is the mass number of the other isotope?

Explanation:

Step1: Recall the concept of isotopes

Gallium has two naturally - occurring isotopes. The sum of their abundances is 100%.

Step2: Calculate the abundance of the second isotope

Let the abundance of the second isotope be $x$. Then $x=100 - 39.892=60.108\%$.

Step3: Recall the relationship between isotopes and mass numbers

The mass number of an isotope is a whole - number approximation of its isotopic mass. Gallium has an atomic number of 31. The two common isotopes of gallium are $^{69}Ga$ and $^{71}Ga$. Since one isotope is $^{71}Ga$, the other isotope is $^{69}Ga$.

Answer:

69