Question

If an atom has 7 protons, 8 neutrons and 9 electrons, what is the mass number?

Answer 1

Its mass number is 15

And this element is nitrogen N

Step-by-step explanation:

Because mass number = number of proton + number of neutrons

So 7+ 8 = 15

Answer 2

mass = protons + neutrons
7+8 = 15 g