Question: An atom of tin has an atomic number of 50 and a mass number of 119. How many protons, electrons, and neutrons are found in one neutral atom of tin?

  Options: 
 A. 50 protons, 69 electrons, 50 neutrons
 B. 50 protons, 50 electrons, 69 neutrons
 C. 69 protons, 50 electrons, 69 neutrons
 D. 69 protons, 69 electrons, 50 neutrons 
Answer: B