The total mass of the protons in an atom of gold-198 is approximately
(1) 79 atomic mass units
(2) 119 atomic mass units
(3) 198 atomic mass units
(4) 277 atomic mass units
Gold has an atomic number of 79 Protons have a relative mass of 1 Gold-198 is a radioactive isotope of gold, which means it has a different number of neutrons, but the same number of protons and electrons So the answer is (1) 79 atomic mass units
