gsfan11
contestada

What is the mass number of an isotope of this atom that has 2 neutrons (Shows 1 Proton in picture

Respuesta :

Mass number = # of protons + # of neutrons. 
Therefore, the mass number is 2+1 = 3
This is probably a Hydrogen isotope called Tritium that contains 2 neutrons, 1 proton, and has a mass number of 3. 

Hope that helps.