Gallium Has an Average Atomic Mass of 69 ${ }_{31}^{72} \mathrm{Ga}$

question 39

Multiple Choice

Gallium has an average atomic mass of 69.7 amu.In a typical sample,60.4% of Ga exists as Ga-69 (68.9257 amu) .What is the identity and the atomic mass of the other isotope?

• A) \({ }_{31}^{72} \mathrm{Ga}\) ;70.9 amu
• B) \({ }_{31}^{70} \mathrm{Ga}\) ;70.9 amu
• C) \({ }_{31}^{71} \mathrm{Ga}\) ;70.9 amu
• D) \({ }_{31}^{71} \mathrm{Ga}\) ;71.9 amu
• E) \({ }_{31}^{72} \mathrm{Ga}\) ;71.9 amu

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