Gallium has an atomic mass of 69.723 amu.The Ga-69 (68.926 amu)is 60.11%.What is the amu of the other isotope?
A) 70.924 amu
B) 70.928 amu
C) 70.932 amu
D) 70.920 amu

Question

Quizplus · Accepted Answer

The atomic mass of Gallium (69.723 amu) is a weighted average of its isotopes. Given that Ga-69 has a mass of 68.926 amu and an abundance of 60.11%, we can calculate the mass of the other isotope (let's call it X) using the formula for average atomic mass: (0.6011)(68.926 amu) + (1-0.6011)(X amu) = 69.723 amu. Solving for X gives us approximately 70.924 amu.

Gallium Has an Atomic Mass of 69