Gallium has an 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) (top:70, bottom:30) Ga; 70.9 amu
b) (top:70, bottom:31) Ga; 70.9 amu
c) (top:71, bottom:31) Ga; 70.9 amu
d) (top:71, bottom:31) Ga; 71.9 amu
e) (top:72, bottom:31) Ga; 71.9 amu