What is the mass number of an element having 20 neutrons, 15 protons and 15 electrons?

Answer Details

The mass number of an element is the sum of its protons and neutrons. In this case, the element has 15 protons and 20 neutrons, so the mass number would be: Mass number = protons + neutrons Mass number = 15 + 20 Mass number = 35 Therefore, the correct option is 35. To summarize, the mass number of an element can be found by adding the number of protons and neutrons in the nucleus of an atom.