Question

What is the mass number of an
atom of oxygen with 8 protons and 9
neutrons?

Answer 1

17 is the mass number.

Step-by-step explanation:

(8 protons + 9 neutrons) = 17

Answer 2

16 AMU (Atomic Mass Units).

Step-by-step explanation:

Since it is neutral, it also has eight protons! The periodic table has another number associated with every element, and that is it's atomic mass. For oxygen, the atomic mass is 16 AMU (Atomic Mass Units).