Answer:
The answer to your question is c 11 because the number of neutrons plus protons equals the atomic mass.
Step-by-step explanation:
To calculate the atomic mass of a single atom of an element, add up the mass of protons and neutrons. Example: Find the atomic mass of an isotope of carbon that has 7 neutrons. You can see from the periodic table that carbon has an atomic number of 6, which is its number of protons.